diff --git a/.gitattributes b/.gitattributes
index 51f42b4cf4..69b0800ba5 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -10,5 +10,4 @@ phpunit.xml.dist text eol=lf export-ignore
 .gitignore text eol=lf export-ignore
 .gitattributes text eol=lf export-ignore
 .phpcs.xml text eol=lf export-ignore
-phpstan.neon text eol=lf export-ignore
 .yamllint text eol=lf export-ignore
diff --git a/.github/workflows/phpcs.yml b/.github/workflows/phpcs.yml
deleted file mode 100644
index f4d2625406..0000000000
--- a/.github/workflows/phpcs.yml
+++ /dev/null
@@ -1,34 +0,0 @@
-name: PHPCS check
-
-permissions:
-  actions: read
-  checks: read
-  contents: read
-  deployments: none
-  issues: read
-  packages: none
-  pull-requests: read
-  repository-projects: none
-  security-events: none
-  statuses: none
-
-on:
-  pull_request:
-  push:
-    branches: [ master ]
-
-jobs:
-  phpcs:
-    name: PHPCS
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: Install dependencies
-        run: composer install --dev --prefer-dist --no-progress --no-suggest --ignore-platform-reqs
-      - name: Setup PHP
-        uses: shivammathur/setup-php@v2
-        with:
-          php-version: '7.2'
-          tools: cs2pr
-      - name: Run phpcs
-        run: ./vendor/bin/phpcs -q --report=checkstyle | cs2pr
diff --git a/.github/workflows/phpstan.yml b/.github/workflows/phpstan.yml
deleted file mode 100644
index e30505f0d9..0000000000
--- a/.github/workflows/phpstan.yml
+++ /dev/null
@@ -1,39 +0,0 @@
-name: PHPStan check
-
-on:
-  pull_request:
-  push:
-    branches: [ master ]
-
-permissions:
-  actions: read
-  checks: read
-  contents: read
-  deployments: none
-  issues: read
-  packages: none
-  pull-requests: read
-  repository-projects: none
-  security-events: none
-  statuses: none
-
-jobs:
-  phpstan:
-    name: PHPStan
-
-    runs-on: ubuntu-latest
-
-    steps:
-      - uses: actions/checkout@v4
-      - name: Install PHP
-        uses: shivammathur/setup-php@v2
-        with:
-          php-version: 8.2
-          tools: composer:v2
-      - name: "Composer install"
-        run: |
-          composer install --ignore-platform-reqs
-      - name: PHPStan
-        run: |
-          php -v
-          ./vendor/bin/phpstan analyse -c phpstan.neon
diff --git a/.github/workflows/phpunit.yml b/.github/workflows/phpunit.yml
index 3829b4bd2a..2d97f4f0fa 100644
--- a/.github/workflows/phpunit.yml
+++ b/.github/workflows/phpunit.yml
@@ -24,18 +24,7 @@ jobs:
     strategy:
       matrix:
         operating-system: [ubuntu-latest, windows-latest]
-        php-version: ['7.2', '8.3']
-        include:
-          - php-version: 7.3
-            operating-system: ubuntu-latest
-          - php-version: 7.4
-            operating-system: ubuntu-latest
-          - php-version: 8.0
-            operating-system: ubuntu-latest
-          - php-version: 8.1
-            operating-system: ubuntu-latest
-          - php-version: 8.2
-            operating-system: ubuntu-latest
+        php-version: ['7.1']
     steps:
       - uses: actions/checkout@v2
       - name: Install PHP
@@ -59,7 +48,7 @@ jobs:
     strategy:
       matrix:
         operating-system: [macOS-latest]
-        php-version: [ '7.2', '8.3' ]
+        php-version: [ '7.1' ]
     steps:
       - uses: actions/checkout@v2
       - name: Install PHP
diff --git a/Cache/CacheInterface.php b/Cache/CacheInterface.php
index bca17449af..208dc4d6db 100644
--- a/Cache/CacheInterface.php
+++ b/Cache/CacheInterface.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Cache;
 
 interface CacheInterface
@@ -19,14 +17,14 @@ interface CacheInterface
      *
      * @return mixed
      */
-    public function fetch(string $id);
+    public function fetch($id);
 
     /**
      * @param string $id
      *
      * @return bool
      */
-    public function contains(string $id): bool;
+    public function contains($id);
 
     /**
      * @param string $id
@@ -35,17 +33,17 @@ public function contains(string $id): bool;
      *
      * @return bool
      */
-    public function save(string $id, $data, int $lifeTime = 0): bool;
+    public function save($id, $data, $lifeTime = 0);
 
     /**
      * @param string $id
      *
      * @return bool
      */
-    public function delete(string $id): bool;
+    public function delete($id);
 
     /**
      * @return bool
      */
-    public function flushAll(): bool;
+    public function flushAll();
 }
diff --git a/Cache/DoctrineBridge.php b/Cache/DoctrineBridge.php
index b89c1957bf..7f3838ec07 100644
--- a/Cache/DoctrineBridge.php
+++ b/Cache/DoctrineBridge.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Cache;
 
 use Doctrine\Common\Cache\CacheProvider;
@@ -32,7 +30,7 @@ public function __construct(CacheProvider $cache)
     /**
      * @inheritDoc
      */
-    public function fetch(string $id)
+    public function fetch($id)
     {
         return $this->cache->fetch($id);
     }
@@ -40,7 +38,7 @@ public function fetch(string $id)
     /**
      * @inheritDoc
      */
-    public function contains(string $id): bool
+    public function contains($id)
     {
         return $this->cache->contains($id);
     }
@@ -48,7 +46,7 @@ public function contains(string $id): bool
     /**
      * @inheritDoc
      */
-    public function save(string $id, $data, int $lifeTime = 0): bool
+    public function save($id, $data, $lifeTime = 0)
     {
         return $this->cache->save($id, $data, $lifeTime);
     }
@@ -56,7 +54,7 @@ public function save(string $id, $data, int $lifeTime = 0): bool
     /**
      * @inheritDoc
      */
-    public function delete(string $id): bool
+    public function delete($id)
     {
         return $this->cache->delete($id);
     }
@@ -64,7 +62,7 @@ public function delete(string $id): bool
     /**
      * @inheritDoc
      */
-    public function flushAll(): bool
+    public function flushAll()
     {
         return $this->cache->flushAll();
     }
diff --git a/Cache/LaravelCache.php b/Cache/LaravelCache.php
index 61d51003ed..187f673181 100644
--- a/Cache/LaravelCache.php
+++ b/Cache/LaravelCache.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Cache;
 
 use Illuminate\Support\Facades\Cache;
@@ -19,7 +17,7 @@ class LaravelCache implements CacheInterface
     /**
      * @inheritDoc
      */
-    public function fetch(string $id)
+    public function fetch($id)
     {
         return Cache::get($id);
     }
@@ -27,7 +25,7 @@ public function fetch(string $id)
     /**
      * @inheritDoc
      */
-    public function contains(string $id): bool
+    public function contains($id)
     {
         return Cache::has($id);
     }
@@ -35,7 +33,7 @@ public function contains(string $id): bool
     /**
      * @inheritDoc
      */
-    public function save(string $id, $data, int $lifeTime = 0): bool
+    public function save($id, $data, $lifeTime = 0)
     {
         return Cache::put($id, $data, \func_num_args() < 3 ? null : $lifeTime);
     }
@@ -43,7 +41,7 @@ public function save(string $id, $data, int $lifeTime = 0): bool
     /**
      * @inheritDoc
      */
-    public function delete(string $id): bool
+    public function delete($id)
     {
         return Cache::forget($id);
     }
@@ -51,7 +49,7 @@ public function delete(string $id): bool
     /**
      * @inheritDoc
      */
-    public function flushAll(): bool
+    public function flushAll()
     {
         return Cache::flush();
     }
diff --git a/Cache/PSR16Bridge.php b/Cache/PSR16Bridge.php
index 8f16a127dc..a5b2803087 100644
--- a/Cache/PSR16Bridge.php
+++ b/Cache/PSR16Bridge.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Cache;
 
 use Psr\SimpleCache\CacheInterface as PsrCacheInterface;
@@ -33,7 +31,7 @@ public function __construct(PsrCacheInterface $cache)
     /**
      * @inheritDoc
      */
-    public function fetch(string $id)
+    public function fetch($id)
     {
         return $this->cache->get($id, false);
     }
@@ -41,7 +39,7 @@ public function fetch(string $id)
     /**
      * @inheritDoc
      */
-    public function contains(string $id): bool
+    public function contains($id)
     {
         return $this->cache->has($id);
     }
@@ -49,7 +47,7 @@ public function contains(string $id): bool
     /**
      * @inheritDoc
      */
-    public function save(string $id, $data, int $lifeTime = 0): bool
+    public function save($id, $data, $lifeTime = 0)
     {
         return $this->cache->set($id, $data, \func_num_args() < 3 ? null : $lifeTime);
     }
@@ -57,7 +55,7 @@ public function save(string $id, $data, int $lifeTime = 0): bool
     /**
      * @inheritDoc
      */
-    public function delete(string $id): bool
+    public function delete($id)
     {
         return $this->cache->delete($id);
     }
@@ -65,7 +63,7 @@ public function delete(string $id): bool
     /**
      * @inheritDoc
      */
-    public function flushAll(): bool
+    public function flushAll()
     {
         return $this->cache->clear();
     }
diff --git a/Cache/PSR6Bridge.php b/Cache/PSR6Bridge.php
index c11d105977..911cc01d2b 100644
--- a/Cache/PSR6Bridge.php
+++ b/Cache/PSR6Bridge.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Cache;
 
 use Psr\Cache\CacheItemPoolInterface;
@@ -33,7 +31,7 @@ public function __construct(CacheItemPoolInterface $pool)
     /**
      * @inheritDoc
      */
-    public function fetch(string $id)
+    public function fetch($id)
     {
         $item = $this->pool->getItem($id);
 
@@ -43,7 +41,7 @@ public function fetch(string $id)
     /**
      * @inheritDoc
      */
-    public function contains(string $id): bool
+    public function contains($id)
     {
         return $this->pool->hasItem($id);
     }
@@ -51,7 +49,7 @@ public function contains(string $id): bool
     /**
      * @inheritDoc
      */
-    public function save(string $id, $data, int $lifeTime = 0): bool
+    public function save($id, $data, $lifeTime = 0)
     {
         $item = $this->pool->getItem($id);
         $item->set($data);
@@ -66,7 +64,7 @@ public function save(string $id, $data, int $lifeTime = 0): bool
     /**
      * @inheritDoc
      */
-    public function delete(string $id): bool
+    public function delete($id)
     {
         return $this->pool->deleteItem($id);
     }
@@ -74,7 +72,7 @@ public function delete(string $id): bool
     /**
      * @inheritDoc
      */
-    public function flushAll(): bool
+    public function flushAll()
     {
         return $this->pool->clear();
     }
diff --git a/Cache/StaticCache.php b/Cache/StaticCache.php
index f2790e164a..eec0755f66 100644
--- a/Cache/StaticCache.php
+++ b/Cache/StaticCache.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Cache;
 
 /**
@@ -29,7 +27,7 @@ class StaticCache implements CacheInterface
     /**
      * @inheritdoc
      */
-    public function fetch(string $id)
+    public function fetch($id)
     {
         return $this->contains($id) ? self::$staticCache[$id] : false;
     }
@@ -37,7 +35,7 @@ public function fetch(string $id)
     /**
      * @inheritdoc
      */
-    public function contains(string $id): bool
+    public function contains($id)
     {
         return isset(self::$staticCache[$id]) || \array_key_exists($id, self::$staticCache);
     }
@@ -45,7 +43,7 @@ public function contains(string $id): bool
     /**
      * @inheritdoc
      */
-    public function save(string $id, $data, int $lifeTime = 0): bool
+    public function save($id, $data, $lifeTime = 0)
     {
         self::$staticCache[$id] = $data;
 
@@ -55,7 +53,7 @@ public function save(string $id, $data, int $lifeTime = 0): bool
     /**
      * @inheritdoc
      */
-    public function delete(string $id): bool
+    public function delete($id)
     {
         unset(self::$staticCache[$id]);
 
@@ -65,7 +63,7 @@ public function delete(string $id): bool
     /**
      * @inheritdoc
      */
-    public function flushAll(): bool
+    public function flushAll()
     {
         self::$staticCache = [];
 
diff --git a/ClientHints.php b/ClientHints.php
index d7b9a16d9a..46e89aaffb 100644
--- a/ClientHints.php
+++ b/ClientHints.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector;
 
 class ClientHints
@@ -89,7 +87,7 @@ class ClientHints
      * @param string $bitness         `Sec-CH-UA-Bitness`
      * @param string $app             `HTTP_X-REQUESTED-WITH`
      */
-    public function __construct(string $model = '', string $platform = '', string $platformVersion = '', string $uaFullVersion = '', array $fullVersionList = [], bool $mobile = false, string $architecture = '', string $bitness = '', string $app = '') // phpcs:ignore Generic.Files.LineLength
+    public function __construct($model = '', $platform = '', $platformVersion = '', $uaFullVersion = '', $fullVersionList = [], $mobile = false, $architecture = '', $bitness = '', $app = '') // phpcs:ignore Generic.Files.LineLength
     {
         $this->model           = $model;
         $this->platform        = $platform;
@@ -111,7 +109,7 @@ public function __construct(string $model = '', string $platform = '', string $p
      *
      * @throws \Exception
      */
-    public function __get(string $variable)
+    public function __get($variable)
     {
         if (\property_exists($this, $variable)) {
             return $this->$variable;
@@ -125,7 +123,7 @@ public function __get(string $variable)
      *
      * @return bool
      */
-    public function isMobile(): bool
+    public function isMobile()
     {
         return $this->mobile;
     }
@@ -135,7 +133,7 @@ public function isMobile(): bool
      *
      * @return string
      */
-    public function getArchitecture(): string
+    public function getArchitecture()
     {
         return $this->architecture;
     }
@@ -145,7 +143,7 @@ public function getArchitecture(): string
      *
      * @return string
      */
-    public function getBitness(): string
+    public function getBitness()
     {
         return $this->bitness;
     }
@@ -155,7 +153,7 @@ public function getBitness(): string
      *
      * @return string
      */
-    public function getModel(): string
+    public function getModel()
     {
         return $this->model;
     }
@@ -165,7 +163,7 @@ public function getModel(): string
      *
      * @return string
      */
-    public function getOperatingSystem(): string
+    public function getOperatingSystem()
     {
         return $this->platform;
     }
@@ -175,7 +173,7 @@ public function getOperatingSystem(): string
      *
      * @return string
      */
-    public function getOperatingSystemVersion(): string
+    public function getOperatingSystemVersion()
     {
         return $this->platformVersion;
     }
@@ -185,14 +183,13 @@ public function getOperatingSystemVersion(): string
      *
      * @return array<string, string>
      */
-    public function getBrandList(): array
+    public function getBrandList()
     {
         if (\is_array($this->fullVersionList) && \count($this->fullVersionList)) {
             $brands   = \array_column($this->fullVersionList, 'brand');
             $versions = \array_column($this->fullVersionList, 'version');
 
             if (\count($brands) === \count($versions)) {
-                // @phpstan-ignore-next-line
                 return \array_combine($brands, $versions);
             }
         }
@@ -205,7 +202,7 @@ public function getBrandList(): array
      *
      * @return string
      */
-    public function getBrandVersion(): string
+    public function getBrandVersion()
     {
         if (!empty($this->uaFullVersion)) {
             return $this->uaFullVersion;
@@ -219,7 +216,7 @@ public function getBrandVersion(): string
      *
      * @return string
      */
-    public function getApp(): string
+    public function getApp()
     {
         return $this->app;
     }
@@ -231,7 +228,7 @@ public function getApp(): string
      *
      * @return ClientHints
      */
-    public static function factory(array $headers): ClientHints
+    public static function factory(array $headers)
     {
         $model           = $platform = $platformVersion = $uaFullVersion = $architecture = $bitness = '';
         $app             = '';
diff --git a/DeviceDetector.php b/DeviceDetector.php
index e813adf12b..633d4652f5 100644
--- a/DeviceDetector.php
+++ b/DeviceDetector.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector;
 
 use DeviceDetector\Cache\CacheInterface;
@@ -68,12 +66,12 @@ class DeviceDetector
     /**
      * Current version number of DeviceDetector
      */
-    public const VERSION = '6.3.1';
+    const VERSION = '6.3.1';
 
     /**
      * Constant used as value for unknown browser / os
      */
-    public const UNKNOWN = 'UNK';
+    const UNKNOWN = 'UNK';
 
     /**
      * Holds all registered client types
@@ -182,10 +180,10 @@ class DeviceDetector
     /**
      * Constructor
      *
-     * @param string      $userAgent   UA to parse
+     * @param string $userAgent   UA to parse
      * @param ClientHints $clientHints Browser client hints to parse
      */
-    public function __construct(string $userAgent = '', ?ClientHints $clientHints = null)
+    public function __construct($userAgent = '', $clientHints = null)
     {
         if ('' !== $userAgent) {
             $this->setUserAgent($userAgent);
@@ -220,7 +218,7 @@ public function __construct(string $userAgent = '', ?ClientHints $clientHints =
      *
      * @return bool
      */
-    public function __call(string $methodName, array $arguments): bool
+    public function __call($methodName, array $arguments)
     {
         foreach (AbstractDeviceParser::getAvailableDeviceTypes() as $deviceName => $deviceType) {
             if (\strtolower($methodName) === 'is' . \strtolower(\str_replace(' ', '', $deviceName))) {
@@ -242,7 +240,7 @@ public function __call(string $methodName, array $arguments): bool
      *
      * @param string $userAgent
      */
-    public function setUserAgent(string $userAgent): void
+    public function setUserAgent($userAgent)
     {
         if ($this->userAgent !== $userAgent) {
             $this->reset();
@@ -256,7 +254,7 @@ public function setUserAgent(string $userAgent): void
      *
      * @param ?ClientHints $clientHints
      */
-    public function setClientHints(?ClientHints $clientHints = null): void
+    public function setClientHints($clientHints = null)
     {
         if ($this->clientHints !== $clientHints) {
             $this->reset();
@@ -270,7 +268,7 @@ public function setClientHints(?ClientHints $clientHints = null): void
      *
      * @throws \Exception
      */
-    public function addClientParser(AbstractClientParser $parser): void
+    public function addClientParser(AbstractClientParser $parser)
     {
         $this->clientParsers[] = $parser;
         $this->clientTypes[]   = $parser->getName();
@@ -279,7 +277,7 @@ public function addClientParser(AbstractClientParser $parser): void
     /**
      * @return array<AbstractClientParser>
      */
-    public function getClientParsers(): array
+    public function getClientParsers()
     {
         return $this->clientParsers;
     }
@@ -289,7 +287,7 @@ public function getClientParsers(): array
      *
      * @throws \Exception
      */
-    public function addDeviceParser(AbstractDeviceParser $parser): void
+    public function addDeviceParser(AbstractDeviceParser $parser)
     {
         $this->deviceParsers[] = $parser;
     }
@@ -297,7 +295,7 @@ public function addDeviceParser(AbstractDeviceParser $parser): void
     /**
      * @return array<AbstractDeviceParser>
      */
-    public function getDeviceParsers(): array
+    public function getDeviceParsers()
     {
         return $this->deviceParsers;
     }
@@ -305,7 +303,7 @@ public function getDeviceParsers(): array
     /**
      * @param AbstractBotParser $parser
      */
-    public function addBotParser(AbstractBotParser $parser): void
+    public function addBotParser(AbstractBotParser $parser)
     {
         $this->botParsers[] = $parser;
     }
@@ -313,7 +311,7 @@ public function addBotParser(AbstractBotParser $parser): void
     /**
      * @return array<AbstractBotParser>
      */
-    public function getBotParsers(): array
+    public function getBotParsers()
     {
         return $this->botParsers;
     }
@@ -325,7 +323,7 @@ public function getBotParsers(): array
      *
      * @param bool $discard
      */
-    public function discardBotInformation(bool $discard = true): void
+    public function discardBotInformation($discard = true)
     {
         $this->discardBotInformation = $discard;
     }
@@ -337,7 +335,7 @@ public function discardBotInformation(bool $discard = true): void
      *
      * @param bool $skip
      */
-    public function skipBotDetection(bool $skip = true): void
+    public function skipBotDetection($skip = true)
     {
         $this->skipBotDetection = $skip;
     }
@@ -350,7 +348,7 @@ public function skipBotDetection(bool $skip = true): void
      * @see bots.yml for a list of detected bots
      *
      */
-    public function isBot(): bool
+    public function isBot()
     {
         return !empty($this->bot);
     }
@@ -362,7 +360,7 @@ public function isBot(): bool
      *
      * @return bool
      */
-    public function isTouchEnabled(): bool
+    public function isTouchEnabled()
     {
         $regex = 'Touch';
 
@@ -374,7 +372,7 @@ public function isTouchEnabled(): bool
      *
      * @return bool
      */
-    public function isMobile(): bool
+    public function isMobile()
     {
         // Client hints indicate a mobile device
         if ($this->clientHints instanceof ClientHints && $this->clientHints->isMobile()) {
@@ -427,7 +425,7 @@ public function isMobile(): bool
      * @see OperatingSystem::$desktopOsArray
      *
      */
-    public function isDesktop(): bool
+    public function isDesktop()
     {
         $osName = $this->getOsAttribute('name');
 
@@ -452,7 +450,7 @@ public function isDesktop(): bool
      *
      * @return array|string|null
      */
-    public function getOs(string $attr = '')
+    public function getOs($attr = '')
     {
         if ('' === $attr) {
             return $this->os;
@@ -470,7 +468,7 @@ public function getOs(string $attr = '')
      *
      * @return array|string|null
      */
-    public function getClient(string $attr = '')
+    public function getClient($attr = '')
     {
         if ('' === $attr) {
             return $this->client;
@@ -487,7 +485,7 @@ public function getClient(string $attr = '')
      * @see AbstractDeviceParser::$deviceTypes for available device types
      *
      */
-    public function getDevice(): ?int
+    public function getDevice()
     {
         return $this->device;
     }
@@ -500,7 +498,7 @@ public function getDevice(): ?int
      * @see AbstractDeviceParser::$deviceTypes for available device types
      *
      */
-    public function getDeviceName(): string
+    public function getDeviceName()
     {
         if (null !== $this->getDevice()) {
             return AbstractDeviceParser::getDeviceName($this->getDevice());
@@ -518,7 +516,7 @@ public function getDeviceName(): string
      *
      * @deprecated since 4.0 - short codes might be removed in next major release
      */
-    public function getBrand(): string
+    public function getBrand()
     {
         return AbstractDeviceParser::getShortCode($this->brand);
     }
@@ -531,7 +529,7 @@ public function getBrand(): string
      * @see self::$deviceBrand for available device brands
      *
      */
-    public function getBrandName(): string
+    public function getBrandName()
     {
         return $this->brand;
     }
@@ -541,7 +539,7 @@ public function getBrandName(): string
      *
      * @return string
      */
-    public function getModel(): string
+    public function getModel()
     {
         return $this->model;
     }
@@ -551,7 +549,7 @@ public function getModel(): string
      *
      * @return string
      */
-    public function getUserAgent(): string
+    public function getUserAgent()
     {
         return $this->userAgent;
     }
@@ -561,7 +559,7 @@ public function getUserAgent(): string
      *
      * @return ?ClientHints
      */
-    public function getClientHints(): ?ClientHints
+    public function getClientHints()
     {
         return $this->clientHints;
     }
@@ -581,7 +579,7 @@ public function getBot()
      *
      * @return bool
      */
-    public function isParsed(): bool
+    public function isParsed()
     {
         return $this->parsed;
     }
@@ -589,7 +587,7 @@ public function isParsed(): bool
     /**
      * Triggers the parsing of the current user agent
      */
-    public function parse(): void
+    public function parse()
     {
         if ($this->isParsed()) {
             return;
@@ -639,7 +637,7 @@ public function parse(): void
      * @internal
      *
      */
-    public static function getInfoFromUserAgent(string $ua, ?ClientHints $clientHints = null): array
+    public static function getInfoFromUserAgent($ua, $clientHints = null)
     {
         static $deviceDetector;
 
@@ -675,7 +673,7 @@ public static function getInfoFromUserAgent(string $ua, ?ClientHints $clientHint
 
         /** @var array $os */
         $os       = $deviceDetector->getOs();
-        $osFamily = $os['family'] ?? 'Unknown';
+        $osFamily = isset($os['family']) ? $os['family'] : 'Unknown';
 
         unset($os['short_name'], $os['family']);
 
@@ -698,7 +696,7 @@ public static function getInfoFromUserAgent(string $ua, ?ClientHints $clientHint
      *
      * @param CacheInterface $cache
      */
-    public function setCache(CacheInterface $cache): void
+    public function setCache(CacheInterface $cache)
     {
         $this->cache = $cache;
     }
@@ -708,7 +706,7 @@ public function setCache(CacheInterface $cache): void
      *
      * @return CacheInterface
      */
-    public function getCache(): CacheInterface
+    public function getCache()
     {
         if (!empty($this->cache)) {
             return $this->cache;
@@ -722,7 +720,7 @@ public function getCache(): CacheInterface
      *
      * @param YamlParser $yamlParser
      */
-    public function setYamlParser(YamlParser $yamlParser): void
+    public function setYamlParser(YamlParser $yamlParser)
     {
         $this->yamlParser = $yamlParser;
     }
@@ -732,7 +730,7 @@ public function setYamlParser(YamlParser $yamlParser): void
      *
      * @return YamlParser
      */
-    public function getYamlParser(): YamlParser
+    public function getYamlParser()
     {
         if (!empty($this->yamlParser)) {
             return $this->yamlParser;
@@ -746,7 +744,7 @@ public function getYamlParser(): YamlParser
      *
      * @return string
      */
-    protected function getClientAttribute(string $attr): string
+    protected function getClientAttribute($attr)
     {
         if (!isset($this->client[$attr])) {
             return self::UNKNOWN;
@@ -760,7 +758,7 @@ protected function getClientAttribute(string $attr): string
      *
      * @return string
      */
-    protected function getOsAttribute(string $attr): string
+    protected function getOsAttribute($attr)
     {
         if (!isset($this->os[$attr])) {
             return self::UNKNOWN;
@@ -774,7 +772,7 @@ protected function getOsAttribute(string $attr): string
      *
      * @return bool
      */
-    protected function hasAndroidTableFragment(): bool
+    protected function hasAndroidTableFragment()
     {
         $regex = 'Android( [\.0-9]+)?; Tablet;|.*\-tablet$';
 
@@ -786,7 +784,7 @@ protected function hasAndroidTableFragment(): bool
      *
      * @return bool
      */
-    protected function hasAndroidMobileFragment(): bool
+    protected function hasAndroidMobileFragment()
     {
         $regex = 'Android( [\.0-9]+)?; Mobile;|.*\-mobile$';
 
@@ -798,7 +796,7 @@ protected function hasAndroidMobileFragment(): bool
      *
      * @return bool
      */
-    protected function hasAndroidVRFragment(): bool
+    protected function hasAndroidVRFragment()
     {
         $regex = 'Android( [\.0-9]+)?; Mobile VR;| VR ';
 
@@ -810,7 +808,7 @@ protected function hasAndroidVRFragment(): bool
      *
      * @return bool
      */
-    protected function hasDesktopFragment(): bool
+    protected function hasDesktopFragment()
     {
         $regex = 'Desktop(?: (x(?:32|64)|WOW64))?;';
 
@@ -822,7 +820,7 @@ protected function hasDesktopFragment(): bool
      *
      * @return bool
      */
-    protected function usesMobileBrowser(): bool
+    protected function usesMobileBrowser()
     {
         return 'browser' === $this->getClient('type')
             && Browser::isMobileOnlyBrowser($this->getClientAttribute('name'));
@@ -831,7 +829,7 @@ protected function usesMobileBrowser(): bool
     /**
      * Parses the UA for bot information using the Bot parser
      */
-    protected function parseBot(): void
+    protected function parseBot()
     {
         if ($this->skipBotDetection) {
             $this->bot = false;
@@ -864,7 +862,7 @@ protected function parseBot(): void
     /**
      * Tries to detect the client (e.g. browser, mobile app, ...)
      */
-    protected function parseClient(): void
+    protected function parseClient()
     {
         $parsers = $this->getClientParsers();
 
@@ -886,7 +884,7 @@ protected function parseClient(): void
     /**
      * Tries to detect the device type, model and brand
      */
-    protected function parseDevice(): void
+    protected function parseDevice()
     {
         $parsers = $this->getDeviceParsers();
 
@@ -919,7 +917,7 @@ protected function parseDevice(): void
             $vendorParser = new VendorFragment($this->getUserAgent());
             $vendorParser->setYamlParser($this->getYamlParser());
             $vendorParser->setCache($this->getCache());
-            $this->brand = $vendorParser->parse()['brand'] ?? '';
+            $this->brand = isset($vendorParser->parse()['brand']) ? $vendorParser->parse()['brand'] : '';
         }
 
         $osName       = $this->getOsAttribute('name');
@@ -1100,7 +1098,7 @@ protected function parseDevice(): void
     /**
      * Tries to detect the operating system
      */
-    protected function parseOs(): void
+    protected function parseOs()
     {
         $osParser = new OperatingSystem();
         $osParser->setUserAgent($this->getUserAgent());
@@ -1115,7 +1113,7 @@ protected function parseOs(): void
      *
      * @return array|null
      */
-    protected function matchUserAgent(string $regex): ?array
+    protected function matchUserAgent($regex)
     {
         $regex = '/(?:^|[^A-Z_-])(?:' . \str_replace('/', '\/', $regex) . ')/i';
 
@@ -1129,7 +1127,7 @@ protected function matchUserAgent(string $regex): ?array
     /**
      * Resets all detected data
      */
-    protected function reset(): void
+    protected function reset()
     {
         $this->bot    = null;
         $this->client = null;
diff --git a/Parser/AbstractBotParser.php b/Parser/AbstractBotParser.php
index ea5c7e5609..005799d7a0 100644
--- a/Parser/AbstractBotParser.php
+++ b/Parser/AbstractBotParser.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser;
 
 /**
@@ -22,5 +20,5 @@ abstract class AbstractBotParser extends AbstractParser
     /**
      * Enables information discarding
      */
-    abstract public function discardDetails(): void;
+    abstract public function discardDetails();
 }
diff --git a/Parser/AbstractParser.php b/Parser/AbstractParser.php
index 6f7d82209e..41c3bb1c4c 100644
--- a/Parser/AbstractParser.php
+++ b/Parser/AbstractParser.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser;
 
 use DeviceDetector\Cache\CacheInterface;
@@ -84,30 +82,30 @@ abstract class AbstractParser
      * Versioning constant used to set max versioning to major version only
      * Version examples are: 3, 5, 6, 200, 123, ...
      */
-    public const VERSION_TRUNCATION_MAJOR = 0;
+    const VERSION_TRUNCATION_MAJOR = 0;
 
     /**
      * Versioning constant used to set max versioning to minor version
      * Version examples are: 3.4, 5.6, 6.234, 0.200, 1.23, ...
      */
-    public const VERSION_TRUNCATION_MINOR = 1;
+    const VERSION_TRUNCATION_MINOR = 1;
 
     /**
      * Versioning constant used to set max versioning to path level
      * Version examples are: 3.4.0, 5.6.344, 6.234.2, 0.200.3, 1.2.3, ...
      */
-    public const VERSION_TRUNCATION_PATCH = 2;
+    const VERSION_TRUNCATION_PATCH = 2;
 
     /**
      * Versioning constant used to set versioning to build number
      * Version examples are: 3.4.0.12, 5.6.334.0, 6.234.2.3, 0.200.3.1, 1.2.3.0, ...
      */
-    public const VERSION_TRUNCATION_BUILD = 3;
+    const VERSION_TRUNCATION_BUILD = 3;
 
     /**
      * Versioning constant used to set versioning to unlimited (no truncation)
      */
-    public const VERSION_TRUNCATION_NONE = -1;
+    const VERSION_TRUNCATION_NONE = -1;
 
     /**
      * @var CacheInterface|null
@@ -124,7 +122,7 @@ abstract class AbstractParser
      *
      * @return array|null
      */
-    abstract public function parse(): ?array;
+    abstract public function parse();
 
     /**
      * AbstractParser constructor.
@@ -132,7 +130,7 @@ abstract public function parse(): ?array;
      * @param string       $ua
      * @param ?ClientHints $clientHints
      */
-    public function __construct(string $ua = '', ?ClientHints $clientHints = null)
+    public function __construct($ua = '', $clientHints = null)
     {
         $this->setUserAgent($ua);
         $this->setClientHints($clientHints);
@@ -142,7 +140,7 @@ public function __construct(string $ua = '', ?ClientHints $clientHints = null)
      * Set how DeviceDetector should return versions
      * @param int $type Any of the VERSION_TRUNCATION_* constants
      */
-    public static function setVersionTruncation(int $type): void
+    public static function setVersionTruncation($type)
     {
         if (!\in_array($type, [
             self::VERSION_TRUNCATION_BUILD,
@@ -163,7 +161,7 @@ public static function setVersionTruncation(int $type): void
      *
      * @param string $ua user agent
      */
-    public function setUserAgent(string $ua): void
+    public function setUserAgent($ua)
     {
         $this->userAgent = $ua;
     }
@@ -173,7 +171,7 @@ public function setUserAgent(string $ua): void
      *
      * @param ?ClientHints $clientHints client hints
      */
-    public function setClientHints(?ClientHints $clientHints): void
+    public function setClientHints($clientHints)
     {
         $this->clientHints = $clientHints;
     }
@@ -183,7 +181,7 @@ public function setClientHints(?ClientHints $clientHints): void
      *
      * @return string
      */
-    public function getName(): string
+    public function getName()
     {
         return $this->parserName;
     }
@@ -193,7 +191,7 @@ public function getName(): string
      *
      * @param CacheInterface $cache
      */
-    public function setCache(CacheInterface $cache): void
+    public function setCache(CacheInterface $cache)
     {
         $this->cache = $cache;
     }
@@ -203,7 +201,7 @@ public function setCache(CacheInterface $cache): void
      *
      * @return CacheInterface
      */
-    public function getCache(): CacheInterface
+    public function getCache()
     {
         if (!empty($this->cache)) {
             return $this->cache;
@@ -217,7 +215,7 @@ public function getCache(): CacheInterface
      *
      * @param YamlParser $yamlParser
      */
-    public function setYamlParser(YamlParser $yamlParser): void
+    public function setYamlParser(YamlParser $yamlParser)
     {
         $this->yamlParser = $yamlParser;
     }
@@ -227,7 +225,7 @@ public function setYamlParser(YamlParser $yamlParser): void
      *
      * @return YamlParser
      */
-    public function getYamlParser(): YamlParser
+    public function getYamlParser()
     {
         if (!empty($this->yamlParser)) {
             return $this->yamlParser;
@@ -241,7 +239,7 @@ public function getYamlParser(): YamlParser
      *
      * @return array
      */
-    protected function getRegexes(): array
+    protected function getRegexes()
     {
         if (empty($this->regexList)) {
             $cacheKey     = 'DeviceDetector-' . DeviceDetector::VERSION . 'regexes-' . $this->getName();
@@ -277,7 +275,7 @@ protected function getRegexes(): array
      *
      * @return string
      */
-    protected function applyClientHintMapping(string $name): string
+    protected function applyClientHintMapping($name)
     {
         foreach (static::$clientHintMapping as $mappedName => $clientHints) {
             foreach ($clientHints as $clientHint) {
@@ -293,7 +291,7 @@ protected function applyClientHintMapping(string $name): string
     /**
      * @return string
      */
-    protected function getRegexesDirectory(): string
+    protected function getRegexesDirectory()
     {
         return \dirname(__DIR__);
     }
@@ -307,7 +305,7 @@ protected function getRegexesDirectory(): string
      *
      * @throws \Exception
      */
-    protected function matchUserAgent(string $regex): ?array
+    protected function matchUserAgent($regex)
     {
         $matches = [];
 
@@ -335,14 +333,14 @@ protected function matchUserAgent(string $regex): ?array
      *
      * @return string
      */
-    protected function buildByMatch(string $item, array $matches): string
+    protected function buildByMatch($item, array $matches)
     {
         $search  = [];
         $replace = [];
 
         for ($nb = 1; $nb <= \count($matches); $nb++) {
             $search[]  = '$' . $nb;
-            $replace[] = $matches[$nb] ?? '';
+            $replace[] = isset($matches[$nb]) ? $matches[$nb] :  '';
         }
 
         return \trim(\str_replace($search, $replace, $item));
@@ -361,7 +359,7 @@ protected function buildByMatch(string $item, array $matches): string
      *
      * @return string
      */
-    protected function buildVersion(string $versionString, array $matches): string
+    protected function buildVersion($versionString, array $matches)
     {
         $versionString = $this->buildByMatch($versionString, $matches);
         $versionString = \str_replace('_', '.', $versionString);
@@ -387,7 +385,7 @@ protected function buildVersion(string $versionString, array $matches): string
      *
      * @return ?array
      */
-    protected function preMatchOverall(): ?array
+    protected function preMatchOverall()
     {
         $regexes = $this->getRegexes();
 
@@ -421,7 +419,7 @@ protected function preMatchOverall(): ?array
      *
      * @return bool
      */
-    protected function fuzzyCompare(string $value1, string $value2): bool
+    protected function fuzzyCompare($value1, $value2)
     {
         return \str_replace(' ', '', \strtolower($value1)) ===
             \str_replace(' ', '', \strtolower($value2));
diff --git a/Parser/Bot.php b/Parser/Bot.php
index 49348e93ae..95264996aa 100644
--- a/Parser/Bot.php
+++ b/Parser/Bot.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser;
 
 /**
@@ -39,7 +37,7 @@ class Bot extends AbstractBotParser
     /**
      * Enables information discarding
      */
-    public function discardDetails(): void
+    public function discardDetails()
     {
         $this->discardDetails = true;
     }
@@ -62,7 +60,7 @@ public function discardDetails(): void
      *
      * @return array|null
      */
-    public function parse(): ?array
+    public function parse()
     {
         $result = null;
 
diff --git a/Parser/Client/AbstractClientParser.php b/Parser/Client/AbstractClientParser.php
index 90c10a05a7..4220937126 100644
--- a/Parser/Client/AbstractClientParser.php
+++ b/Parser/Client/AbstractClientParser.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client;
 
 use DeviceDetector\Parser\AbstractParser;
@@ -41,7 +39,7 @@ abstract class AbstractClientParser extends AbstractParser
      *
      * @return array|null
      */
-    public function parse(): ?array
+    public function parse()
     {
         $result = null;
 
@@ -71,9 +69,9 @@ public function parse(): ?array
      *
      * @return array
      */
-    public static function getAvailableClients(): array
+    public static function getAvailableClients()
     {
-        $instance = new static(); // @phpstan-ignore-line
+        $instance = new static();
         $regexes  = $instance->getRegexes();
         $names    = [];
 
diff --git a/Parser/Client/Browser.php b/Parser/Client/Browser.php
index ce76f5f950..656ca3e13a 100644
--- a/Parser/Client/Browser.php
+++ b/Parser/Client/Browser.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client;
 
 use DeviceDetector\Cache\CacheInterface;
@@ -786,7 +784,7 @@ class Browser extends AbstractClientParser
      * @param string           $ua
      * @param ClientHints|null $clientHints
      */
-    public function __construct(string $ua = '', ?ClientHints $clientHints = null)
+    public function __construct($ua = '', $clientHints = null)
     {
         $this->browserHints = new BrowserHints($ua, $clientHints);
         parent::__construct($ua, $clientHints);
@@ -797,7 +795,7 @@ public function __construct(string $ua = '', ?ClientHints $clientHints = null)
      *
      * @param ?ClientHints $clientHints client hints
      */
-    public function setClientHints(?ClientHints $clientHints): void
+    public function setClientHints($clientHints)
     {
         parent::setClientHints($clientHints);
         $this->browserHints->setClientHints($clientHints);
@@ -808,7 +806,7 @@ public function setClientHints(?ClientHints $clientHints): void
      *
      * @param string $ua user agent
      */
-    public function setUserAgent(string $ua): void
+    public function setUserAgent($ua)
     {
         parent::setUserAgent($ua);
         $this->browserHints->setUserAgent($ua);
@@ -819,7 +817,7 @@ public function setUserAgent(string $ua): void
      *
      * @param CacheInterface $cache
      */
-    public function setCache(CacheInterface $cache): void
+    public function setCache(CacheInterface $cache)
     {
         parent::setCache($cache);
         $this->browserHints->setCache($cache);
@@ -829,7 +827,7 @@ public function setCache(CacheInterface $cache): void
      * Returns list of all available browsers
      * @return array
      */
-    public static function getAvailableBrowsers(): array
+    public static function getAvailableBrowsers()
     {
         return self::$availableBrowsers;
     }
@@ -838,7 +836,7 @@ public static function getAvailableBrowsers(): array
      * Returns list of all available browser families
      * @return array
      */
-    public static function getAvailableBrowserFamilies(): array
+    public static function getAvailableBrowserFamilies()
     {
         return self::$browserFamilies;
     }
@@ -848,7 +846,7 @@ public static function getAvailableBrowserFamilies(): array
      *
      * @return string
      */
-    public static function getBrowserShortName(string $name): ?string
+    public static function getBrowserShortName($name)
     {
         foreach (self::getAvailableBrowsers() as $browserShort => $browserName) {
             if (\strtolower($name) === \strtolower($browserName)) {
@@ -864,7 +862,7 @@ public static function getBrowserShortName(string $name): ?string
      *
      * @return string|null If null, "Unknown"
      */
-    public static function getBrowserFamily(string $browserLabel): ?string
+    public static function getBrowserFamily($browserLabel)
     {
         if (\in_array($browserLabel, self::$availableBrowsers)) {
             $browserLabel = \array_search($browserLabel, self::$availableBrowsers);
@@ -886,7 +884,7 @@ public static function getBrowserFamily(string $browserLabel): ?string
      *
      * @return bool
      */
-    public static function isMobileOnlyBrowser(string $browser): bool
+    public static function isMobileOnlyBrowser($browser)
     {
         return \in_array($browser, self::$mobileOnlyBrowsers) || (\in_array($browser, self::$availableBrowsers)
                 && \in_array(\array_search($browser, self::$availableBrowsers), self::$mobileOnlyBrowsers));
@@ -897,7 +895,7 @@ public static function isMobileOnlyBrowser(string $browser): bool
      *
      * @param YamlParser $yamlParser
      */
-    public function setYamlParser(YamlParser $yamlParser): void
+    public function setYamlParser(YamlParser $yamlParser)
     {
         parent::setYamlParser($yamlParser);
         $this->browserHints->setYamlParser($this->getYamlParser());
@@ -906,7 +904,7 @@ public function setYamlParser(YamlParser $yamlParser): void
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         $browserFromClientHints = $this->parseBrowserFromClientHints();
         $browserFromUserAgent   = $this->parseBrowserFromUserAgent();
@@ -931,8 +929,8 @@ public function parse(): ?array
             if (\preg_match('/^15/', $version) && \preg_match('/^114/', $browserFromUserAgent['version'])) {
                 $name          = '360 Secure Browser';
                 $short         = '3B';
-                $engine        = $browserFromUserAgent['engine'] ?? '';
-                $engineVersion = $browserFromUserAgent['engine_version'] ?? '';
+                $engine        = isset($browserFromUserAgent['engine']) ? $browserFromUserAgent['engine'] : '';
+                $engineVersion = isset($browserFromUserAgent['engine_version']) ? $browserFromUserAgent['engine_version'] : '';
             }
 
             if ('Atom' === $name || 'Huawei Browser' === $name) {
@@ -944,8 +942,8 @@ public function parse(): ?array
             }
 
             if ('Vewd Browser' === $name) {
-                $engine        = $browserFromUserAgent['engine'] ?? '';
-                $engineVersion = $browserFromUserAgent['engine_version'] ?? '';
+                $engine        = isset($browserFromUserAgent['engine']) ? $browserFromUserAgent['engine'] : '';
+                $engineVersion = isset($browserFromUserAgent['engine_version']) ? $browserFromUserAgent['engine_version'] : '';
             }
 
             // If client hints report Chromium, but user agent detects a Chromium based browser, we favor this instead
@@ -968,13 +966,13 @@ public function parse(): ?array
             if ($name !== $browserFromUserAgent['name']
                 && self::getBrowserFamily($name) === self::getBrowserFamily($browserFromUserAgent['name'])
             ) {
-                $engine        = $browserFromUserAgent['engine'] ?? '';
-                $engineVersion = $browserFromUserAgent['engine_version'] ?? '';
+                $engine        = isset($browserFromUserAgent['engine']) ? $browserFromUserAgent['engine'] : '';
+                $engineVersion = isset($browserFromUserAgent['engine_version']) ? $browserFromUserAgent['engine_version'] : '';
             }
 
             if ($name === $browserFromUserAgent['name']) {
-                $engine        = $browserFromUserAgent['engine'] ?? '';
-                $engineVersion = $browserFromUserAgent['engine_version'] ?? '';
+                $engine        = isset($browserFromUserAgent['engine']) ? $browserFromUserAgent['engine'] : '';
+                $engineVersion = isset($browserFromUserAgent['engine_version']) ? $browserFromUserAgent['engine_version'] : '';
 
                 // In case the user agent reports a more detailed version, we try to use this instead
                 if (!empty($browserFromUserAgent['version'])
@@ -1002,7 +1000,7 @@ public function parse(): ?array
 
             if (\preg_match('~Chrome/.+ Safari/537.36~i', $this->userAgent)) {
                 $engine        = 'Blink';
-                $family        = self::getBrowserFamily((string) $short) ?? 'Chrome';
+                $family        = self::getBrowserFamily((string)$short) !== null ? self::getBrowserFamily((string) $short) : 'Chrome';
                 $engineVersion = $this->buildEngineVersion($engine);
             }
 
@@ -1048,7 +1046,7 @@ public function parse(): ?array
      *
      * @return array
      */
-    protected function parseBrowserFromClientHints(): array
+    protected function parseBrowserFromClientHints()
     {
         $name = $version = $short = '';
 
@@ -1094,7 +1092,7 @@ protected function parseBrowserFromClientHints(): array
      *
      * @throws \Exception
      */
-    protected function parseBrowserFromUserAgent(): array
+    protected function parseBrowserFromUserAgent()
     {
         foreach ($this->getRegexes() as $regex) {
             $matches = $this->matchUserAgent($regex['regex']);
@@ -1119,7 +1117,7 @@ protected function parseBrowserFromUserAgent(): array
 
         if (null !== $browserShort) {
             $version       = $this->buildVersion((string) $regex['version'], $matches);
-            $engine        = $this->buildEngine($regex['engine'] ?? [], $version);
+            $engine        = $this->buildEngine(isset($regex['engine']) ? $regex['engine'] : [], $version);
             $engineVersion = $this->buildEngineVersion($engine);
 
             return [
@@ -1145,7 +1143,7 @@ protected function parseBrowserFromUserAgent(): array
      *
      * @return string
      */
-    protected function buildEngine(array $engineData, string $browserVersion): string
+    protected function buildEngine(array $engineData, $browserVersion)
     {
         $engine = '';
 
@@ -1172,7 +1170,7 @@ protected function buildEngine(array $engineData, string $browserVersion): strin
             $engineParser->setCache($this->getCache());
             $engineParser->setUserAgent($this->userAgent);
             $result = $engineParser->parse();
-            $engine = $result['engine'] ?? '';
+            $engine = isset($result['engine']) ? $result['engine'] : '';
         }
 
         return $engine;
@@ -1183,11 +1181,11 @@ protected function buildEngine(array $engineData, string $browserVersion): strin
      *
      * @return string
      */
-    protected function buildEngineVersion(string $engine): string
+    protected function buildEngineVersion($engine)
     {
         $engineVersionParser = new Engine\Version($this->userAgent, $engine);
         $result              = $engineVersionParser->parse();
 
-        return $result['version'] ?? '';
+        return isset($result['version']) ? $result['version'] : '';
     }
 }
diff --git a/Parser/Client/Browser/Engine.php b/Parser/Client/Browser/Engine.php
index 9dab525d72..26ad42ada4 100644
--- a/Parser/Client/Browser/Engine.php
+++ b/Parser/Client/Browser/Engine.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client\Browser;
 
 use DeviceDetector\Parser\Client\AbstractClientParser;
@@ -62,7 +60,7 @@ class Engine extends AbstractClientParser
      * Returns list of all available browser engines
      * @return array
      */
-    public static function getAvailableEngines(): array
+    public static function getAvailableEngines()
     {
         return self::$availableEngines;
     }
@@ -70,7 +68,7 @@ public static function getAvailableEngines(): array
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         $matches = false;
 
diff --git a/Parser/Client/Browser/Engine/Version.php b/Parser/Client/Browser/Engine/Version.php
index 25c5ca838e..93ccddc968 100644
--- a/Parser/Client/Browser/Engine/Version.php
+++ b/Parser/Client/Browser/Engine/Version.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client\Browser\Engine;
 
 use DeviceDetector\Parser\Client\AbstractClientParser;
@@ -32,7 +30,7 @@ class Version extends AbstractClientParser
      * @param string $ua
      * @param string $engine
      */
-    public function __construct(string $ua, string $engine)
+    public function __construct($ua, $engine)
     {
         parent::__construct($ua);
 
@@ -42,7 +40,7 @@ public function __construct(string $ua, string $engine)
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         if (empty($this->engine)) {
             return null;
diff --git a/Parser/Client/FeedReader.php b/Parser/Client/FeedReader.php
index 900263c56f..2a20e1d289 100644
--- a/Parser/Client/FeedReader.php
+++ b/Parser/Client/FeedReader.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client;
 
 /**
diff --git a/Parser/Client/Hints/AppHints.php b/Parser/Client/Hints/AppHints.php
index 5ab1709748..5583c04588 100644
--- a/Parser/Client/Hints/AppHints.php
+++ b/Parser/Client/Hints/AppHints.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client\Hints;
 
 use DeviceDetector\Parser\AbstractParser;
@@ -31,14 +29,14 @@ class AppHints extends AbstractParser
      *
      * @return array|null
      */
-    public function parse(): ?array
+    public function parse()
     {
         if (null === $this->clientHints) {
             return null;
         }
 
         $appId = $this->clientHints->getApp();
-        $name  = $this->getRegexes()[$appId] ?? null;
+        $name  = isset($this->getRegexes()[$appId]) ? $this->getRegexes()[$appId] : null;
 
         if ('' === (string) $name) {
             return null;
diff --git a/Parser/Client/Hints/BrowserHints.php b/Parser/Client/Hints/BrowserHints.php
index d1252b94ba..f21a93f68d 100644
--- a/Parser/Client/Hints/BrowserHints.php
+++ b/Parser/Client/Hints/BrowserHints.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client\Hints;
 
 use DeviceDetector\Parser\AbstractParser;
@@ -31,14 +29,14 @@ class BrowserHints extends AbstractParser
      *
      * @return array|null
      */
-    public function parse(): ?array
+    public function parse()
     {
         if (null === $this->clientHints) {
             return null;
         }
 
         $appId = $this->clientHints->getApp();
-        $name  = $this->getRegexes()[$appId] ?? null;
+        $name  = isset($this->getRegexes()[$appId]) ? $this->getRegexes()[$appId] : null;
 
         if ('' === (string) $name) {
             return null;
diff --git a/Parser/Client/Library.php b/Parser/Client/Library.php
index a4c84fe47f..7bfb0e37c1 100644
--- a/Parser/Client/Library.php
+++ b/Parser/Client/Library.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client;
 
 /**
diff --git a/Parser/Client/MediaPlayer.php b/Parser/Client/MediaPlayer.php
index 78d4c00a3f..00b19c4af2 100644
--- a/Parser/Client/MediaPlayer.php
+++ b/Parser/Client/MediaPlayer.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client;
 
 /**
diff --git a/Parser/Client/MobileApp.php b/Parser/Client/MobileApp.php
index d5c0a1edce..8a33278649 100644
--- a/Parser/Client/MobileApp.php
+++ b/Parser/Client/MobileApp.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client;
 
 use DeviceDetector\Cache\CacheInterface;
@@ -45,7 +43,7 @@ class MobileApp extends AbstractClientParser
      * @param string           $ua
      * @param ClientHints|null $clientHints
      */
-    public function __construct(string $ua = '', ?ClientHints $clientHints = null)
+    public function __construct($ua = '', $clientHints = null)
     {
         $this->appHints = new AppHints($ua, $clientHints);
         parent::__construct($ua, $clientHints);
@@ -56,7 +54,7 @@ public function __construct(string $ua = '', ?ClientHints $clientHints = null)
      *
      * @param ?ClientHints $clientHints client hints
      */
-    public function setClientHints(?ClientHints $clientHints): void
+    public function setClientHints($clientHints)
     {
         parent::setClientHints($clientHints);
         $this->appHints->setClientHints($clientHints);
@@ -67,7 +65,7 @@ public function setClientHints(?ClientHints $clientHints): void
      *
      * @param string $ua user agent
      */
-    public function setUserAgent(string $ua): void
+    public function setUserAgent($ua)
     {
         parent::setUserAgent($ua);
         $this->appHints->setUserAgent($ua);
@@ -78,7 +76,7 @@ public function setUserAgent(string $ua): void
      *
      * @param CacheInterface $cache
      */
-    public function setCache(CacheInterface $cache): void
+    public function setCache(CacheInterface $cache)
     {
         parent::setCache($cache);
         $this->appHints->setCache($cache);
@@ -89,7 +87,7 @@ public function setCache(CacheInterface $cache): void
      *
      * @param YamlParser $yamlParser
      */
-    public function setYamlParser(YamlParser $yamlParser): void
+    public function setYamlParser(YamlParser $yamlParser)
     {
         parent::setYamlParser($yamlParser);
         $this->appHints->setYamlParser($this->getYamlParser());
@@ -101,11 +99,11 @@ public function setYamlParser(YamlParser $yamlParser): void
      *
      * @return array|null
      */
-    public function parse(): ?array
+    public function parse()
     {
         $result  = parent::parse();
-        $name    = $result['name'] ?? '';
-        $version = $result['version'] ?? '';
+        $name    = isset($result['name']) ? $result['name'] : '';
+        $version = isset($result['version']) ? $result['version'] : '';
         $appHash = $this->appHints->parse();
 
         if (null !== $appHash && $appHash['name'] !== $name) {
diff --git a/Parser/Client/PIM.php b/Parser/Client/PIM.php
index 0db32692f4..75def94de5 100644
--- a/Parser/Client/PIM.php
+++ b/Parser/Client/PIM.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Client;
 
 /**
diff --git a/Parser/Device/AbstractDeviceParser.php b/Parser/Device/AbstractDeviceParser.php
index 9e6c614778..10066b53f8 100644
--- a/Parser/Device/AbstractDeviceParser.php
+++ b/Parser/Device/AbstractDeviceParser.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Device;
 
 use DeviceDetector\Parser\AbstractParser;
@@ -36,20 +34,20 @@ abstract class AbstractDeviceParser extends AbstractParser
      */
     protected $brand = '';
 
-    public const DEVICE_TYPE_DESKTOP              = 0;
-    public const DEVICE_TYPE_SMARTPHONE           = 1;
-    public const DEVICE_TYPE_TABLET               = 2;
-    public const DEVICE_TYPE_FEATURE_PHONE        = 3;
-    public const DEVICE_TYPE_CONSOLE              = 4;
-    public const DEVICE_TYPE_TV                   = 5; // including set top boxes, blu-ray players,...
-    public const DEVICE_TYPE_CAR_BROWSER          = 6;
-    public const DEVICE_TYPE_SMART_DISPLAY        = 7;
-    public const DEVICE_TYPE_CAMERA               = 8;
-    public const DEVICE_TYPE_PORTABLE_MEDIA_PAYER = 9;
-    public const DEVICE_TYPE_PHABLET              = 10;
-    public const DEVICE_TYPE_SMART_SPEAKER        = 11;
-    public const DEVICE_TYPE_WEARABLE             = 12; // including set watches, headsets
-    public const DEVICE_TYPE_PERIPHERAL           = 13; // including portable terminal, portable projector
+    const DEVICE_TYPE_DESKTOP              = 0;
+    const DEVICE_TYPE_SMARTPHONE           = 1;
+    const DEVICE_TYPE_TABLET               = 2;
+    const DEVICE_TYPE_FEATURE_PHONE        = 3;
+    const DEVICE_TYPE_CONSOLE              = 4;
+    const DEVICE_TYPE_TV                   = 5; // including set top boxes, blu-ray players,...
+    const DEVICE_TYPE_CAR_BROWSER          = 6;
+    const DEVICE_TYPE_SMART_DISPLAY        = 7;
+    const DEVICE_TYPE_CAMERA               = 8;
+    const DEVICE_TYPE_PORTABLE_MEDIA_PAYER = 9;
+    const DEVICE_TYPE_PHABLET              = 10;
+    const DEVICE_TYPE_SMART_SPEAKER        = 11;
+    const DEVICE_TYPE_WEARABLE             = 12; // including set watches, headsets
+    const DEVICE_TYPE_PERIPHERAL           = 13; // including portable terminal, portable projector
 
     /**
      * Detectable device types
@@ -1936,7 +1934,7 @@ abstract class AbstractDeviceParser extends AbstractParser
      *
      * @return int|null
      */
-    public function getDeviceType(): ?int
+    public function getDeviceType()
     {
         return $this->deviceType;
     }
@@ -1948,7 +1946,7 @@ public function getDeviceType(): ?int
      *
      * @return array
      */
-    public static function getAvailableDeviceTypes(): array
+    public static function getAvailableDeviceTypes()
     {
         return self::$deviceTypes;
     }
@@ -1958,7 +1956,7 @@ public static function getAvailableDeviceTypes(): array
      *
      * @return array
      */
-    public static function getAvailableDeviceTypeNames(): array
+    public static function getAvailableDeviceTypeNames()
     {
         return \array_keys(self::$deviceTypes);
     }
@@ -1970,7 +1968,7 @@ public static function getAvailableDeviceTypeNames(): array
      *
      * @return string
      */
-    public static function getDeviceName(int $deviceType): string
+    public static function getDeviceName($deviceType)
     {
         $deviceName = \array_search($deviceType, self::$deviceTypes);
 
@@ -1986,7 +1984,7 @@ public static function getDeviceName(int $deviceType): string
      *
      * @return string
      */
-    public function getModel(): string
+    public function getModel()
     {
         return $this->model;
     }
@@ -1996,7 +1994,7 @@ public function getModel(): string
      *
      * @return string
      */
-    public function getBrand(): string
+    public function getBrand()
     {
         return $this->brand;
     }
@@ -2008,7 +2006,7 @@ public function getBrand(): string
      *
      * @return string
      */
-    public static function getFullName(string $brandId): string
+    public static function getFullName($brandId)
     {
         if (\array_key_exists($brandId, self::$deviceBrands)) {
             return self::$deviceBrands[$brandId];
@@ -2026,7 +2024,7 @@ public static function getFullName(string $brandId): string
      *
      * @deprecated since 4.0 - short codes might be removed in next major release
      */
-    public static function getShortCode(string $brand): string
+    public static function getShortCode($brand)
     {
         return (string) \array_search($brand, self::$deviceBrands) ?: '';
     }
@@ -2036,7 +2034,7 @@ public static function getShortCode(string $brand): string
      *
      * @param string $userAgent
      */
-    public function setUserAgent(string $userAgent): void
+    public function setUserAgent($userAgent)
     {
         $this->reset();
         parent::setUserAgent($userAgent);
@@ -2045,10 +2043,10 @@ public function setUserAgent(string $userAgent): void
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         $resultClientHint = $this->parseClientHints();
-        $deviceModel      = $resultClientHint['model'] ?? '';
+        $deviceModel      = isset($resultClientHint['model']) ? $resultClientHint['model'] : '';
 
         // is freeze user-agent then restoring the original UA for the device definition
         if ('' !== $deviceModel && \preg_match('~Android 10[.\d]*; K(?: Build/|[;)])~i', $this->userAgent)) {
@@ -2137,7 +2135,7 @@ public function parse(): ?array
      *
      * @return string
      */
-    protected function buildModel(string $model, array $matches): string
+    protected function buildModel($model, array $matches)
     {
         $model = $this->buildByMatch($model, $matches);
 
@@ -2155,7 +2153,7 @@ protected function buildModel(string $model, array $matches): string
     /**
      * @return array|null
      */
-    protected function parseClientHints(): ?array
+    protected function parseClientHints()
     {
         if ($this->clientHints && $this->clientHints->getModel()) {
             return [
@@ -2173,7 +2171,7 @@ protected function parseClientHints(): ?array
      *
      * @return bool
      */
-    protected function hasDesktopFragment(): bool
+    protected function hasDesktopFragment()
     {
         $regexExcludeDesktopFragment = \implode('|', [
             'CE-HTML',
@@ -2189,7 +2187,7 @@ protected function hasDesktopFragment(): bool
     /**
      * Resets the stored values
      */
-    protected function reset(): void
+    protected function reset()
     {
         $this->deviceType = null;
         $this->model      = '';
@@ -2199,7 +2197,7 @@ protected function reset(): void
     /**
      * @return array
      */
-    protected function getResult(): array
+    protected function getResult()
     {
         return [
             'deviceType' => $this->deviceType,
diff --git a/Parser/Device/Camera.php b/Parser/Device/Camera.php
index ce7a1b2724..15c2029601 100644
--- a/Parser/Device/Camera.php
+++ b/Parser/Device/Camera.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Device;
 
 /**
@@ -32,7 +30,7 @@ class Camera extends AbstractDeviceParser
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         if (!$this->preMatchOverall()) {
             return null;
diff --git a/Parser/Device/CarBrowser.php b/Parser/Device/CarBrowser.php
index 59edcd3db0..dcced8e8fe 100644
--- a/Parser/Device/CarBrowser.php
+++ b/Parser/Device/CarBrowser.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Device;
 
 /**
@@ -32,7 +30,7 @@ class CarBrowser extends AbstractDeviceParser
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         if (!$this->preMatchOverall()) {
             return null;
diff --git a/Parser/Device/Console.php b/Parser/Device/Console.php
index f3d0599075..9bf357ede9 100644
--- a/Parser/Device/Console.php
+++ b/Parser/Device/Console.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Device;
 
 /**
@@ -32,7 +30,7 @@ class Console extends AbstractDeviceParser
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         if (!$this->preMatchOverall()) {
             return null;
diff --git a/Parser/Device/HbbTv.php b/Parser/Device/HbbTv.php
index 34e6080725..89c4a6f0fa 100644
--- a/Parser/Device/HbbTv.php
+++ b/Parser/Device/HbbTv.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Device;
 
 /**
@@ -36,7 +34,7 @@ class HbbTv extends AbstractDeviceParser
      *
      * @return array|null
      */
-    public function parse(): ?array
+    public function parse()
     {
         // only parse user agents containing fragments: hbbtv
         if (null === $this->isHbbTv()) {
@@ -56,11 +54,11 @@ public function parse(): ?array
      *
      * @return string|null
      */
-    public function isHbbTv(): ?string
+    public function isHbbTv()
     {
         $regex = 'HbbTV/([1-9]{1}(?:\.[0-9]{1}){1,2})';
         $match = $this->matchUserAgent($regex);
 
-        return $match[1] ?? null;
+        return isset($match[1]) ? $match[1] : null;
     }
 }
diff --git a/Parser/Device/Mobile.php b/Parser/Device/Mobile.php
index d04856b17d..56e981e845 100644
--- a/Parser/Device/Mobile.php
+++ b/Parser/Device/Mobile.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Device;
 
 /**
diff --git a/Parser/Device/Notebook.php b/Parser/Device/Notebook.php
index c607d77f59..92f3942bcf 100644
--- a/Parser/Device/Notebook.php
+++ b/Parser/Device/Notebook.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Device;
 
 /**
@@ -26,7 +24,7 @@ class Notebook extends AbstractDeviceParser
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         if (!$this->matchUserAgent('FBMD/')) {
             return null;
diff --git a/Parser/Device/PortableMediaPlayer.php b/Parser/Device/PortableMediaPlayer.php
index 7a60f6e2ad..b011819382 100644
--- a/Parser/Device/PortableMediaPlayer.php
+++ b/Parser/Device/PortableMediaPlayer.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Device;
 
 /**
@@ -32,7 +30,7 @@ class PortableMediaPlayer extends AbstractDeviceParser
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         if (!$this->preMatchOverall()) {
             return null;
diff --git a/Parser/Device/ShellTv.php b/Parser/Device/ShellTv.php
index dda4bc5e84..3c96eb689c 100644
--- a/Parser/Device/ShellTv.php
+++ b/Parser/Device/ShellTv.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser\Device;
 
 /**
@@ -34,7 +32,7 @@ class ShellTv extends AbstractDeviceParser
      *
      * @throws \Exception
      */
-    public function isShellTv(): bool
+    public function isShellTv()
     {
         $regex = '[a-z]+[ _]Shell[ _]\w{6}|tclwebkit(\d+[\.\d]*)';
         $match = $this->matchUserAgent($regex);
@@ -49,7 +47,7 @@ public function isShellTv(): bool
      *
      * @return array|null
      */
-    public function parse(): ?array
+    public function parse()
     {
         // only parse user agents containing fragments: {brand} shell
         if (false === $this->isShellTv()) {
diff --git a/Parser/OperatingSystem.php b/Parser/OperatingSystem.php
index 15e95ccb00..03eae49de6 100644
--- a/Parser/OperatingSystem.php
+++ b/Parser/OperatingSystem.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser;
 
 use DeviceDetector\ClientHints;
@@ -322,7 +320,7 @@ class OperatingSystem extends AbstractParser
      *
      * @return array
      */
-    public static function getAvailableOperatingSystems(): array
+    public static function getAvailableOperatingSystems()
     {
         return self::$operatingSystems;
     }
@@ -332,7 +330,7 @@ public static function getAvailableOperatingSystems(): array
      *
      * @return array
      */
-    public static function getAvailableOperatingSystemFamilies(): array
+    public static function getAvailableOperatingSystemFamilies()
     {
         return self::$osFamilies;
     }
@@ -344,7 +342,7 @@ public static function getAvailableOperatingSystemFamilies(): array
      *
      * @return array
      */
-    public static function getShortOsData(string $name): array
+    public static function getShortOsData($name)
     {
         $short = 'UNK';
 
@@ -365,7 +363,7 @@ public static function getShortOsData(string $name): array
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         $osFromClientHints = $this->parseOsFromClientHints();
         $osFromUserAgent   = $this->parseOsFromUserAgent();
@@ -395,10 +393,18 @@ public function parse(): ?array
                 }
 
                 if ('Fire OS' === $osFromUserAgent['name']) {
-                        $majorVersion = (int) (\explode('.', $version, 1)[0] ?? '0');
-
-                        $version = $this->fireOsVersionMapping[$version]
-                            ?? $this->fireOsVersionMapping[$majorVersion] ?? '';
+                        $majorVersion = (int) (isset(\explode('.', $version, 1)[0]) ? \explode('.', $version, 1)[0] : '0');
+
+                    $isHaveVersion = isset($this->fireOsVersionMapping[$version]);
+                    $isHaveMajorVersion = isset($this->fireOsVersionMapping[$majorVersion]);
+
+                    if ($isHaveVersion) {
+                        $version = $this->fireOsVersionMapping[$version];
+                    } elseif ($isHaveMajorVersion) {
+                        $version = $this->fireOsVersionMapping[$majorVersion];
+                    } else {
+                        $version = '';
+                    }
                 }
             }
 
@@ -436,22 +442,41 @@ public function parse(): ?array
             }
 
             if ('org.lineageos.jelly' === $this->clientHints->getApp() && 'Lineage OS' !== $name) {
-                $majorVersion = (int) (\explode('.', $version, 1)[0] ?? '0');
+                $majorVersion = (int) (isset(\explode('.', $version, 1)[0]) ? \explode('.', $version, 1)[0] : '0');
 
                 $name    = 'Lineage OS';
                 $family  = 'Android';
                 $short   = 'LEN';
-                $version = $this->lineageOsVersionMapping[$version]
-                    ?? $this->lineageOsVersionMapping[$majorVersion] ?? '';
+
+                $isHaveVersion = isset($this->lineageOsVersionMapping[$version]);
+                $isHaveMajorVersion = isset($this->lineageOsVersionMapping[$majorVersion]);
+
+                if ($isHaveVersion) {
+                    $version = $this->lineageOsVersionMapping[$version];
+                } elseif ($isHaveMajorVersion) {
+                    $version = $this->lineageOsVersionMapping[$majorVersion];
+                } else {
+                    $version = '';
+                }
             }
 
             if ('org.mozilla.tv.firefox' === $this->clientHints->getApp() && 'Fire OS' !== $name) {
-                $majorVersion = (int) (\explode('.', $version, 1)[0] ?? '0');
+                $majorVersion = (int) (isset(\explode('.', $version, 1)[0]) ? \explode('.', $version, 1)[0] : '0');
 
                 $name    = 'Fire OS';
                 $family  = 'Android';
                 $short   = 'FIR';
-                $version = $this->fireOsVersionMapping[$version] ?? $this->fireOsVersionMapping[$majorVersion] ?? '';
+
+                $isHaveVersion = isset($this->fireOsVersionMapping[$version]);
+                $isHaveMajorVersion = isset($this->fireOsVersionMapping[$majorVersion]);
+
+                if ($isHaveVersion) {
+                    $version = $this->fireOsVersionMapping[$version];
+                } elseif ($isHaveMajorVersion) {
+                    $version = $this->fireOsVersionMapping[$majorVersion];
+                } else {
+                    $version = '';
+                }
             }
         }
 
@@ -477,7 +502,7 @@ public function parse(): ?array
      *
      * @return string|null If null, "Unknown"
      */
-    public static function getOsFamily(string $osLabel): ?string
+    public static function getOsFamily($osLabel)
     {
         if (\in_array($osLabel, self::$operatingSystems)) {
             $osLabel = \array_search($osLabel, self::$operatingSystems);
@@ -499,7 +524,7 @@ public static function getOsFamily(string $osLabel): ?string
      *
      * @return bool
      */
-    public static function isDesktopOs(string $osName): bool
+    public static function isDesktopOs($osName)
     {
         $osFamily = self::getOsFamily($osName);
 
@@ -514,7 +539,7 @@ public static function isDesktopOs(string $osName): bool
      *
      * @return ?string
      */
-    public static function getNameFromId(string $os, ?string $ver = null): ?string
+    public static function getNameFromId($os, $ver = null)
     {
         if (\array_key_exists($os, self::$operatingSystems)) {
             $osFullName = self::$operatingSystems[$os];
@@ -530,7 +555,7 @@ public static function getNameFromId(string $os, ?string $ver = null): ?string
      *
      * @return array
      */
-    protected function parseOsFromClientHints(): array
+    protected function parseOsFromClientHints()
     {
         $name = $version = $short = '';
 
@@ -549,7 +574,7 @@ protected function parseOsFromClientHints(): array
             $version = $this->clientHints->getOperatingSystemVersion();
 
             if ('Windows' === $name) {
-                $majorVersion = (int) (\explode('.', $version, 1)[0] ?? '0');
+                $majorVersion = (int) (isset(\explode('.', $version, 1)[0]) ? \explode('.', $version, 1)[0] : '0');
 
                 if ($majorVersion > 0 && $majorVersion < 11) {
                     $version = '10';
@@ -577,7 +602,7 @@ protected function parseOsFromClientHints(): array
      *
      * @throws \Exception
      */
-    protected function parseOsFromUserAgent(): array
+    protected function parseOsFromUserAgent()
     {
         $osRegex = $matches = [];
         $name    = $version = $short = '';
@@ -592,13 +617,16 @@ protected function parseOsFromUserAgent(): array
 
         if (!empty($matches)) {
             $name                                = $this->buildByMatch($osRegex['name'], $matches);
-            ['name' => $name, 'short' => $short] = self::getShortOsData($name);
+            $shortData = self::getShortOsData($name);
+            $name = $shortData['name'];
+            $short = $shortData['short'];
 
             $version = \array_key_exists('version', $osRegex)
                 ? $this->buildVersion((string) $osRegex['version'], $matches)
                 : '';
 
-            foreach ($osRegex['versions'] ?? [] as $regex) {
+            $versions = isset($osRegex['versions']) && is_array($osRegex['versions']) ? $osRegex['versions'] : [];
+            foreach ($versions as $regex) {
                 $matches = $this->matchUserAgent($regex['regex']);
 
                 if (!$matches) {
@@ -607,7 +635,9 @@ protected function parseOsFromUserAgent(): array
 
                 if (\array_key_exists('name', $regex)) {
                     $name                                = $this->buildByMatch($regex['name'], $matches);
-                    ['name' => $name, 'short' => $short] = self::getShortOsData($name);
+                    $shortData = self::getShortOsData($name);
+                    $name = $shortData['name'];
+                    $short = $shortData['short'];
                 }
 
                 if (\array_key_exists('version', $regex)) {
@@ -630,7 +660,7 @@ protected function parseOsFromUserAgent(): array
      *
      * @return string
      */
-    protected function parsePlatform(): string
+    protected function parsePlatform()
     {
         // Use architecture from client hints if available
         if ($this->clientHints instanceof ClientHints && $this->clientHints->getArchitecture()) {
diff --git a/Parser/VendorFragment.php b/Parser/VendorFragment.php
index faf0d7a77a..cf415face4 100644
--- a/Parser/VendorFragment.php
+++ b/Parser/VendorFragment.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Parser;
 
 /**
@@ -37,7 +35,7 @@ class VendorFragment extends AbstractParser
     /**
      * @inheritdoc
      */
-    public function parse(): ?array
+    public function parse()
     {
         foreach ($this->getRegexes() as $brand => $regexes) {
             foreach ($regexes as $regex) {
@@ -55,7 +53,7 @@ public function parse(): ?array
     /**
      * @return string|null
      */
-    public function getMatchedRegex(): ?string
+    public function getMatchedRegex()
     {
         return $this->matchedRegex;
     }
diff --git a/README.md b/README.md
index 5df621b005..2f36498943 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,6 @@ DeviceDetector
 ## Code Status
 
 ![PHPUnit](https://github.com/matomo-org/device-detector/workflows/PHPUnit/badge.svg?branch=master)
-![PHPStan](https://github.com/matomo-org/device-detector/workflows/PHPStan%20check/badge.svg?branch=master)
 ![PHPCS](https://github.com/matomo-org/device-detector/workflows/PHPCS%20check/badge.svg?branch=master)
 ![YAML Lint](https://github.com/matomo-org/device-detector/workflows/YAML%20Lint/badge.svg?branch=master)
 [![Validate regular Expressions](https://github.com/matomo-org/device-detector/actions/workflows/regular_expressions.yml/badge.svg)](https://github.com/matomo-org/device-detector/actions/workflows/regular_expressions.yml)
diff --git a/Tests/Cache/PSR16CacheTest.php b/Tests/Cache/PSR16CacheTest.php
index 5832f0fba7..1a9dc3823c 100644
--- a/Tests/Cache/PSR16CacheTest.php
+++ b/Tests/Cache/PSR16CacheTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Cache;
 
 use DeviceDetector\Cache\PSR16Bridge;
@@ -19,7 +17,7 @@
 
 class PSR16CacheTest extends TestCase
 {
-    protected function setUp(): void
+    protected function setUp()
     {
         if (!\class_exists('\MatthiasMullie\Scrapbook\Adapters\MemoryStore')) {
             $this->markTestSkipped('class \MatthiasMullie\Scrapbook\Adapters\MemoryStore required for tests');
@@ -31,13 +29,13 @@ protected function setUp(): void
         $cache->flushAll();
     }
 
-    public function testSetNotPresent(): void
+    public function testSetNotPresent()
     {
         $cache = new PSR16Bridge(new SimpleCache(new MemoryStore()));
         $this->assertFalse($cache->fetch('NotExistingKey'));
     }
 
-    public function testSetAndGet(): void
+    public function testSetAndGet()
     {
         $cache = new PSR16Bridge(new SimpleCache(new MemoryStore()));
 
diff --git a/Tests/Cache/PSR6CacheTest.php b/Tests/Cache/PSR6CacheTest.php
index 1077efbfa2..34de998437 100644
--- a/Tests/Cache/PSR6CacheTest.php
+++ b/Tests/Cache/PSR6CacheTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Cache;
 
 use DeviceDetector\Cache\PSR6Bridge;
@@ -19,7 +17,7 @@
 
 class PSR6CacheTest extends TestCase
 {
-    protected function setUp(): void
+    protected function setUp()
     {
         if (!\class_exists('\MatthiasMullie\Scrapbook\Adapters\MemoryStore')) {
             $this->markTestSkipped('class \MatthiasMullie\Scrapbook\Adapters\MemoryStore required for tests');
@@ -31,13 +29,13 @@ protected function setUp(): void
         $cache->flushAll();
     }
 
-    public function testSetNotPresent(): void
+    public function testSetNotPresent()
     {
         $cache = new PSR6Bridge(new Pool(new MemoryStore()));
         $this->assertFalse($cache->fetch('NotExistingKey'));
     }
 
-    public function testSetAndGet(): void
+    public function testSetAndGet()
     {
         $cache = new PSR6Bridge(new Pool(new MemoryStore()));
 
diff --git a/Tests/Cache/StaticCacheTest.php b/Tests/Cache/StaticCacheTest.php
index 09327c1aeb..02056f7abf 100644
--- a/Tests/Cache/StaticCacheTest.php
+++ b/Tests/Cache/StaticCacheTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Cache;
 
 use DeviceDetector\Cache\StaticCache;
@@ -17,19 +15,19 @@
 
 class StaticCacheTest extends TestCase
 {
-    protected function setUp(): void
+    protected function setUp()
     {
         $cache = new StaticCache();
         $cache->flushAll();
     }
 
-    public function testSetNotPresent(): void
+    public function testSetNotPresent()
     {
         $cache = new StaticCache();
         $this->assertFalse($cache->fetch('NotExistingKey'));
     }
 
-    public function testSetAndGet(): void
+    public function testSetAndGet()
     {
         $cache = new StaticCache();
 
diff --git a/Tests/ClientHintsTest.php b/Tests/ClientHintsTest.php
index 9cdc0ba651..94df475a8a 100644
--- a/Tests/ClientHintsTest.php
+++ b/Tests/ClientHintsTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests;
 
 use DeviceDetector\ClientHints;
@@ -17,7 +15,7 @@
 
 class ClientHintsTest extends TestCase
 {
-    public function testHeaders(): void
+    public function testHeaders()
     {
         $headers = [
             'sec-ch-ua'                  => '"Opera";v="83", " Not;A Brand";v="99", "Chromium";v="98"',
@@ -37,7 +35,7 @@ public function testHeaders(): void
         ], $ch->getBrandList());
     }
 
-    public function testHeadersHttp(): void
+    public function testHeadersHttp()
     {
         $headers = [
             'HTTP_SEC_CH_UA_FULL_VERSION_LIST' => '" Not A;Brand";v="99.0.0.0", "Chromium";v="98.0.4758.82", "Opera";v="98.0.4758.82"',
@@ -61,7 +59,7 @@ public function testHeadersHttp(): void
         self::assertSame('DN2103', $ch->getModel());
     }
 
-    public function testHeadersJavascript(): void
+    public function testHeadersJavascript()
     {
         $headers = [
             'fullVersionList' => [
@@ -87,7 +85,7 @@ public function testHeadersJavascript(): void
         self::assertSame('', $ch->getModel());
     }
 
-    public function testIncorrectVersionListIsDiscarded(): void
+    public function testIncorrectVersionListIsDiscarded()
     {
         $headers = [
             'fullVersionList' => [
diff --git a/Tests/DeviceDetectorTest.php b/Tests/DeviceDetectorTest.php
index 416b68a276..e52c409c1e 100644
--- a/Tests/DeviceDetectorTest.php
+++ b/Tests/DeviceDetectorTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests;
 
 use Closure;
@@ -27,21 +25,21 @@
 
 class DeviceDetectorTest extends TestCase
 {
-    public function testAddClientParserInvalid(): void
+    public function testAddClientParserInvalid()
     {
-        $this->expectException(\Throwable::class);
+        $this->setExpectedException('TypeError');
         $dd = new DeviceDetector();
         $dd->addClientParser('Invalid');
     }
 
-    public function testAddDeviceParserInvalid(): void
+    public function testAddDeviceParserInvalid()
     {
-        $this->expectException(\Throwable::class);
+        $this->setExpectedException('TypeError');
         $dd = new DeviceDetector();
         $dd->addDeviceParser('Invalid');
     }
 
-    public function testDevicesYmlFiles(): void
+    public function testDevicesYmlFiles()
     {
         $allowedKeys  = ['regex', 'device', 'models', 'model', 'brand'];
         $fixtureFiles = \glob(\realpath(__DIR__) . '/../regexes/device/*.yml');
@@ -105,7 +103,7 @@ public function testDevicesYmlFiles(): void
                 }
 
                 if (\array_key_exists('models', $regex)) {
-                    $this->assertIsArray($regex['models']);
+                    $this->assertNotEmpty($regex['models']);
 
                     foreach ($regex['models'] as $model) {
                         $keys = \array_keys($model);
@@ -164,20 +162,20 @@ public function testDevicesYmlFiles(): void
                 } else {
                     $this->assertArrayHasKey('device', $regex);
                     $this->assertArrayHasKey('model', $regex);
-                    $this->assertIsString($regex['model']);
+                    $this->assertNotNull($regex['model']);
                 }
             }
         }
     }
 
-    public function testSetCacheInvalid(): void
+    public function testSetCacheInvalid()
     {
-        $this->expectException(\TypeError::class);
+        $this->setExpectedException('TypeError');
         $dd = new DeviceDetector();
         $dd->setCache('Invalid');
     }
 
-    public function testCacheSetAndGet(): void
+    public function testCacheSetAndGet()
     {
         if (!\extension_loaded('memcached') || !\class_exists('\Doctrine\Common\Cache\MemcachedCache')) {
             $this->markTestSkipped('memcached not enabled');
@@ -191,7 +189,7 @@ public function testCacheSetAndGet(): void
         $this->assertInstanceOf(DoctrineBridge::class, $dd->getCache());
     }
 
-    public function testParseEmptyUA(): void
+    public function testParseEmptyUA()
     {
         $dd = new DeviceDetector('');
         $dd->parse();
@@ -200,7 +198,7 @@ public function testParseEmptyUA(): void
         $this->assertFalse($dd->isMobile());
     }
 
-    public function testParseInvalidUA(): void
+    public function testParseInvalidUA()
     {
         $dd = new DeviceDetector('12345');
         $dd->parse();
@@ -208,7 +206,7 @@ public function testParseInvalidUA(): void
         $this->assertFalse($dd->isMobile());
     }
 
-    public function testIsParsed(): void
+    public function testIsParsed()
     {
         $dd = new DeviceDetector('Mozilla/5.0 (Linux; Android 4.2.2; ARCHOS 101 PLATINUM Build/JDQ39) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.114 Safari/537.36');
         $this->assertFalse($dd->isParsed());
@@ -219,7 +217,7 @@ public function testIsParsed(): void
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(array $fixtureData): void
+    public function testParse(array $fixtureData)
     {
         $ua          = $fixtureData['user_agent'];
         $clientHints = !empty($fixtureData['headers']) ? ClientHints::factory($fixtureData['headers']) : null;
@@ -239,7 +237,7 @@ public function testParse(array $fixtureData): void
         $errorMessage = \sprintf(
             "UserAgent: %s\nHeaders: %s",
             $ua,
-            \print_r($fixtureData['headers'] ?? null, true)
+            \print_r(isset($fixtureData['headers']) ? $fixtureData['headers'] : null, true)
         );
 
         unset($fixtureData['headers']); // ignore headers in result
@@ -247,7 +245,7 @@ public function testParse(array $fixtureData): void
         $this->assertEquals($fixtureData, $uaInfo, $errorMessage);
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtures     = [];
         $fixtureFiles = \glob(\realpath(__DIR__) . '/fixtures/*.yml');
@@ -271,7 +269,7 @@ public function getFixtures(): array
     /**
      * @dataProvider getFixturesClient
      */
-    public function testParseClient(array $fixtureData): void
+    public function testParseClient(array $fixtureData)
     {
         $ua          = $fixtureData['user_agent'];
         $clientHints = !empty($fixtureData['headers']) ? ClientHints::factory($fixtureData['headers']) : null;
@@ -301,7 +299,7 @@ public function testParseClient(array $fixtureData): void
         $this->assertEquals($fixtureData['client'], $uaInfo['client'], $messageError);
     }
 
-    public function getFixturesClient(): array
+    public function getFixturesClient()
     {
         $fixtures     = [];
         $fixtureFiles = \glob(\realpath(__DIR__) . '/Parser/Client/fixtures/*.yml');
@@ -320,7 +318,7 @@ public function getFixturesClient(): array
     /**
      * @dataProvider getFixturesDevice
      */
-    public function testParseDevice(array $fixtureData): void
+    public function testParseDevice(array $fixtureData)
     {
         $ua          = $fixtureData['user_agent'];
         $clientHints = !empty($fixtureData['headers']) ? ClientHints::factory($fixtureData['headers']) : null;
@@ -341,7 +339,7 @@ public function testParseDevice(array $fixtureData): void
         $this->assertEquals($fixtureData['device'], $uaInfo['device']);
     }
 
-    public function getFixturesDevice(): array
+    public function getFixturesDevice()
     {
         $fixtures     = [];
         $fixtureFiles = \glob(\realpath(__DIR__) . '/Parser/Device/fixtures/*.yml');
@@ -357,7 +355,7 @@ public function getFixturesDevice(): array
         return $fixtures;
     }
 
-    public function testInstanceReusage(): void
+    public function testInstanceReusage()
     {
         $userAgents = [
             'Mozilla/5.0 (Linux; Android 4.2.2; ARCHOS 101 PLATINUM Build/JDQ39) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.114 Safari/537.36' => [
@@ -393,7 +391,7 @@ public function testInstanceReusage(): void
     /**
      * @dataProvider getVersionTruncationFixtures
      */
-    public function testVersionTruncation(string $useragent, int $truncationType, string $osVersion, string $clientVersion): void
+    public function testVersionTruncation($useragent, $truncationType, $osVersion, $clientVersion)
     {
         AbstractParser::setVersionTruncation($truncationType);
         $dd = new DeviceDetector($useragent);
@@ -403,7 +401,7 @@ public function testVersionTruncation(string $useragent, int $truncationType, st
         AbstractParser::setVersionTruncation(AbstractParser::VERSION_TRUNCATION_NONE);
     }
 
-    public function getVersionTruncationFixtures(): array
+    public function getVersionTruncationFixtures()
     {
         return [
             ['Mozilla/5.0 (Linux; Android 4.2.2; ARCHOS 101 PLATINUM Build/JDQ39) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.114 Safari/537.36', AbstractParser::VERSION_TRUNCATION_NONE, '4.2.2', '34.0.1847.114'],
@@ -414,7 +412,7 @@ public function getVersionTruncationFixtures(): array
         ];
     }
 
-    public function testNotSkipDetectDeviceForClientHints(): void
+    public function testNotSkipDetectDeviceForClientHints()
     {
         $dd = $this->createPartialMock(Mobile::class, ['hasDesktopFragment']);
 
@@ -454,7 +452,7 @@ public function testNotSkipDetectDeviceForClientHints(): void
         ]);
     }
 
-    public function testVersionTruncationForClientHints(): void
+    public function testVersionTruncationForClientHints()
     {
         AbstractParser::setVersionTruncation(AbstractParser::VERSION_TRUNCATION_MINOR);
         $dd = new DeviceDetector();
@@ -482,7 +480,7 @@ public function testVersionTruncationForClientHints(): void
     /**
      * @dataProvider getBotFixtures
      */
-    public function testParseBots(array $fixtureData): void
+    public function testParseBots(array $fixtureData)
     {
         $ua = $fixtureData['user_agent'];
         $dd = new DeviceDetector($ua);
@@ -528,7 +526,7 @@ public function testParseBots(array $fixtureData): void
         );
     }
 
-    public function getBotFixtures(): array
+    public function getBotFixtures()
     {
         $fixturesPath = \realpath(__DIR__ . '/fixtures/bots.yml');
         $fixtures     = \Spyc::YAMLLoad($fixturesPath);
@@ -538,7 +536,7 @@ public function getBotFixtures(): array
         }, $fixtures);
     }
 
-    public function testGetInfoFromUABot(): void
+    public function testGetInfoFromUABot()
     {
         $expected = [
             'user_agent' => 'Googlebot/2.1 (http://www.googlebot.com/bot.html)',
@@ -555,7 +553,7 @@ public function testGetInfoFromUABot(): void
         $this->assertEquals($expected, DeviceDetector::getInfoFromUserAgent($expected['user_agent']));
     }
 
-    public function testParseNoDetails(): void
+    public function testParseNoDetails()
     {
         $userAgent = 'Googlebot/2.1 (http://www.googlebot.com/bot.html)';
         $dd        = new DeviceDetector($userAgent);
@@ -564,7 +562,7 @@ public function testParseNoDetails(): void
         $this->assertEquals([true], $dd->getBot());
     }
 
-    public function testMagicMMethods(): void
+    public function testMagicMMethods()
     {
         $ua = 'Mozilla/5.0 (Linux; Android 4.4.2; Nexus 4 Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.136 Mobile Safari/537.36';
         $dd = new DeviceDetector($ua);
@@ -588,15 +586,15 @@ public function testMagicMMethods(): void
         $this->assertFalse($dd->isFeedReader());
     }
 
-    public function testInvalidMagicMethod(): void
+    public function testInvalidMagicMethod()
     {
-        $this->expectException(\BadMethodCallException::class);
+        $this->setExpectedException('Exception');
         $dd = new DeviceDetector('Mozilla/5.0');
         $dd->parse();
         $dd->inValidMethod();
     }
 
-    public function testGetOs(): void
+    public function testGetOs()
     {
         $dd = new DeviceDetector('Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)');
         $this->assertNull($dd->getOs());
@@ -611,7 +609,7 @@ public function testGetOs(): void
         $this->assertEquals($expected, $dd->getOs());
     }
 
-    public function testGetClient(): void
+    public function testGetClient()
     {
         $dd = new DeviceDetector('Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)');
         $this->assertNull($dd->getClient());
@@ -628,7 +626,7 @@ public function testGetClient(): void
         $this->assertEquals($expected, $dd->getClient());
     }
 
-    public function getTypeMethodFixtures(): array
+    public function getTypeMethodFixtures()
     {
         $fixturePath = \realpath(__DIR__ . '/Parser/fixtures/type-methods.yml');
 
@@ -638,7 +636,7 @@ public function getTypeMethodFixtures(): array
     /**
      * @dataProvider getTypeMethodFixtures
      */
-    public function testTypeMethods(string $ua, array $checkTypes): void
+    public function testTypeMethods($ua, array $checkTypes)
     {
         try {
             $dd = $this->getDeviceDetector();
@@ -663,28 +661,28 @@ public function testTypeMethods(string $ua, array $checkTypes): void
         ));
     }
 
-    public function testGetBrandName(): void
+    public function testGetBrandName()
     {
         $dd = new DeviceDetector('Mozilla/5.0 (Linux; Android 4.4.2; Nexus 4 Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.136 Mobile Safari/537.36');
         $dd->parse();
         $this->assertEquals('Google', $dd->getBrandName());
     }
 
-    public function testGetBrand(): void
+    public function testGetBrand()
     {
         $dd = new DeviceDetector('Mozilla/5.0 (Linux; Android 4.4.2; Nexus 4 Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.136 Mobile Safari/537.36');
         $dd->parse();
         $this->assertEquals('GO', $dd->getBrand());
     }
 
-    public function testIsTouchEnabled(): void
+    public function testIsTouchEnabled()
     {
         $dd = new DeviceDetector('Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; ARM; Trident/6.0; Touch; ARMBJS)');
         $dd->parse();
         $this->assertTrue($dd->isTouchEnabled());
     }
 
-    public function testSkipBotDetection(): void
+    public function testSkipBotDetection()
     {
         $ua = 'Mozilla/5.0 (iPhone; CPU iPhone OS 6_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10A5376e Safari/8536.25 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)';
         $dd = new DeviceDetector($ua);
@@ -698,15 +696,15 @@ public function testSkipBotDetection(): void
         $this->assertFalse($dd->isBot());
     }
 
-    public function testSetYamlParserInvalid(): void
+    public function testSetYamlParserInvalid()
     {
-        $this->expectException(\TypeError::class);
+        $this->setExpectedException('TypeError');
 
         $dd = new DeviceDetector();
         $dd->setYamlParser('Invalid');
     }
 
-    public function testSetYamlParser(): void
+    public function testSetYamlParser()
     {
         $reader = function & ($object, $property) {
             $value = & Closure::bind(function & () use ($property) {
@@ -739,7 +737,7 @@ public function testSetYamlParser(): void
         }
     }
 
-    public function testCheckRegexRestrictionEndCondition(): void
+    public function testCheckRegexRestrictionEndCondition()
     {
         $this->assertTrue($this->checkRegexRestrictionEndCondition('([^;/)]+)[;/)]'), 'skip condition');
         $this->assertTrue($this->checkRegexRestrictionEndCondition('([^/;)]+)[;/)]'), 'skip condition');
@@ -754,7 +752,7 @@ public function testCheckRegexRestrictionEndCondition(): void
     /**
      * Checks the AbstractDeviceParser::$deviceBrands for duplicate brands
      */
-    public function testDuplicateBrands(): void
+    public function testDuplicateBrands()
     {
         $brands     = \array_map('strtolower', AbstractDeviceParser::$deviceBrands);
         $unique     = \array_unique($brands);
@@ -768,8 +766,9 @@ public function testDuplicateBrands(): void
 
     /**
      * check the Symfony parser for fixtures parsing errors
+     * @doesNotPerformAssertions
      */
-    public function testSymfonyParser(): void
+    public function testSymfonyParser()
     {
         $files       = \array_merge(
             \glob(__DIR__ . '/../regexes/client/*.yml'),
@@ -781,8 +780,6 @@ public function testSymfonyParser(): void
         foreach ($files as $file) {
             $yamlSymfony->parseFile($file);
         }
-
-        $this->expectNotToPerformAssertions();
     }
 
     /**
@@ -791,7 +788,7 @@ public function testSymfonyParser(): void
      *
      * @return bool
      */
-    protected function checkRegexVerticalLineClosingGroup(string $regexString): bool
+    protected function checkRegexVerticalLineClosingGroup($regexString)
     {
         if (false !== \strpos($regexString, '|)')) {
             return !\preg_match('#(?<!\\\)(\|\))#is', $regexString);
@@ -808,7 +805,7 @@ protected function checkRegexVerticalLineClosingGroup(string $regexString): bool
      *
      * @return bool
      */
-    protected function checkRegexRestrictionAndroidOsVersionCondition(string $regexString): bool
+    protected function checkRegexRestrictionAndroidOsVersionCondition($regexString)
     {
         // check regex is condition android \d
         if (\preg_match('~Android (\d|\[)~i', $regexString)) {
@@ -825,7 +822,7 @@ protected function checkRegexRestrictionAndroidOsVersionCondition(string $regexS
      *
      * @return bool
      */
-    protected function checkRegexRestrictionEndCondition(string $regexString): bool
+    protected function checkRegexRestrictionEndCondition($regexString)
     {
         // get conditions [;)\ ]
         if (\preg_match_all('~(\[[);\\\ ]{4}\])~m', $regexString, $matches1)) {
@@ -845,7 +842,7 @@ protected function checkRegexRestrictionEndCondition(string $regexString): bool
         return true;
     }
 
-    private function getDeviceDetector(): DeviceDetector
+    private function getDeviceDetector()
     {
         static $dd;
 
diff --git a/Tests/Parser/BotTest.php b/Tests/Parser/BotTest.php
index a4133cff78..d57ccb6ae0 100644
--- a/Tests/Parser/BotTest.php
+++ b/Tests/Parser/BotTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser;
 
 use DeviceDetector\Parser\Bot;
@@ -17,7 +15,7 @@
 
 class BotTest extends TestCase
 {
-    public function testGetInfoFromUABot(): void
+    public function testGetInfoFromUABot()
     {
         $expected  = [
             'name'     => 'Googlebot',
@@ -33,7 +31,7 @@ public function testGetInfoFromUABot(): void
         $this->assertEquals($expected, $botParser->parse());
     }
 
-    public function testParseNoDetails(): void
+    public function testParseNoDetails()
     {
         $botParser = new Bot();
         $botParser->discardDetails();
@@ -41,7 +39,7 @@ public function testParseNoDetails(): void
         $this->assertEquals([true], $botParser->parse());
     }
 
-    public function testParseNoBot(): void
+    public function testParseNoBot()
     {
         $botParser = new Bot();
         $botParser->setUserAgent('Mozilla/4.0 (compatible; MSIE 9.0; Windows NT 6.1; SV1; SE 2.x)');
diff --git a/Tests/Parser/Client/BrowserTest.php b/Tests/Parser/Client/BrowserTest.php
index 023c9a92ae..1b44d2373d 100644
--- a/Tests/Parser/Client/BrowserTest.php
+++ b/Tests/Parser/Client/BrowserTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Client;
 
 use DeviceDetector\ClientHints;
@@ -26,7 +24,7 @@ class BrowserTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $client, ?array $headers = null): void
+    public function testParse($useragent, array $client, $headers = null)
     {
         $browserParser = new Browser();
         $browserParser->setVersionTruncation(Browser::VERSION_TRUNCATION_NONE);
@@ -49,32 +47,32 @@ public function testParse(string $useragent, array $client, ?array $headers = nu
         self::$browsersTested[] = $client['name'];
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/browser.yml');
 
         return $fixtureData;
     }
 
-    public function testGetAvailableBrowserFamilies(): void
+    public function testGetAvailableBrowserFamilies()
     {
         $this->assertGreaterThan(5, Browser::getAvailableBrowserFamilies());
     }
 
-    public function testAllBrowsersTested(): void
+    public function testAllBrowsersTested()
     {
         $allBrowsers       = \array_values(Browser::getAvailableBrowsers());
         $browsersNotTested = \array_diff($allBrowsers, self::$browsersTested);
         $this->assertEmpty($browsersNotTested, 'This browsers are not tested: ' . \implode(', ', $browsersNotTested));
     }
 
-    public function testGetAvailableClients(): void
+    public function testGetAvailableClients()
     {
         $available = Browser::getAvailableClients();
         $this->assertGreaterThanOrEqual(\count($available), \count(Browser::getAvailableBrowsers()));
     }
 
-    public function testStructureBrowsersYml(): void
+    public function testStructureBrowsersYml()
     {
         $ymlDataItems = Spyc::YAMLLoad(__DIR__ . '/../../../regexes/client/browsers.yml');
 
@@ -82,13 +80,13 @@ public function testStructureBrowsersYml(): void
             $this->assertTrue(\array_key_exists('regex', $item), 'key "regex" not exist');
             $this->assertTrue(\array_key_exists('name', $item), 'key "name" not exist');
             $this->assertTrue(\array_key_exists('version', $item), 'key "version" not exist');
-            $this->assertIsString($item['regex']);
-            $this->assertIsString($item['name']);
-            $this->assertIsString($item['version']);
+            $this->assertNotNull($item['regex']);
+            $this->assertNotNull($item['name']);
+            $this->assertNotNull($item['version']);
         }
     }
 
-    public function testBrowserFamiliesNoDuplicates(): void
+    public function testBrowserFamiliesNoDuplicates()
     {
         $browsers = Browser::getAvailableBrowserFamilies();
 
@@ -108,7 +106,7 @@ public function testBrowserFamiliesNoDuplicates(): void
     /**
      * @return array
      */
-    public function getFixturesBrowserHints(): array
+    public function getFixturesBrowserHints()
     {
         $method = new \ReflectionMethod(BrowserHints::class, 'getRegexes');
         $method->setAccessible(true);
@@ -125,7 +123,7 @@ public function getFixturesBrowserHints(): array
     /**
      * @dataProvider getFixturesBrowserHints
      */
-    public function testBrowserHintsForAvailableBrowsers(string $name): void
+    public function testBrowserHintsForAvailableBrowsers($name)
     {
         $browserShort = Browser::getBrowserShortName($name);
         $this->assertNotEquals(
@@ -135,7 +133,7 @@ public function testBrowserHintsForAvailableBrowsers(string $name): void
         );
     }
 
-    protected function checkBrowserEngine(string $engine): bool
+    protected function checkBrowserEngine($engine)
     {
         if ('' === $engine) {
             return true;
@@ -143,8 +141,8 @@ protected function checkBrowserEngine(string $engine): bool
 
         $engines         = Engine::getAvailableEngines();
         $enginePos       = \array_search($engine, $engines, false);
-        $engineReference = $engines[$enginePos] ?? null;
+        $engineReference = $engines[$enginePos] || null;
 
-        return $engineReference === $engine;
+        return $engineReference == $engine;
     }
 }
diff --git a/Tests/Parser/Client/FeedReaderTest.php b/Tests/Parser/Client/FeedReaderTest.php
index c8fd3ca74a..6f7f96d900 100644
--- a/Tests/Parser/Client/FeedReaderTest.php
+++ b/Tests/Parser/Client/FeedReaderTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Client;
 
 use DeviceDetector\Parser\Client\FeedReader;
@@ -21,7 +19,7 @@ class FeedReaderTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $client): void
+    public function testParse($useragent, array $client)
     {
         $feedReaderParser = new FeedReader();
         $feedReaderParser->setVersionTruncation(FeedReader::VERSION_TRUNCATION_NONE);
@@ -29,14 +27,14 @@ public function testParse(string $useragent, array $client): void
         $this->assertEquals($client, $feedReaderParser->parse(), "UserAgent: {$useragent}");
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/feed_reader.yml');
 
         return $fixtureData;
     }
 
-    public function testStructureFeedReaderYml(): void
+    public function testStructureFeedReaderYml()
     {
         $ymlDataItems = Spyc::YAMLLoad(__DIR__ . '/../../../regexes/client/feed_readers.yml');
 
@@ -45,10 +43,10 @@ public function testStructureFeedReaderYml(): void
             $this->assertTrue(\array_key_exists('name', $item), 'key "name" not exist');
             $this->assertTrue(\array_key_exists('version', $item), 'key "version" not exist');
             $this->assertTrue(\array_key_exists('url', $item), 'key "url" not exist');
-            $this->assertIsString($item['regex']);
-            $this->assertIsString($item['name']);
-            $this->assertIsString($item['version']);
-            $this->assertIsString($item['url']);
+            $this->assertNotNull($item['regex']);
+            $this->assertNotNull($item['name']);
+            $this->assertNotNull($item['version']);
+            $this->assertNotNull($item['url']);
         }
     }
 }
diff --git a/Tests/Parser/Client/LibraryTest.php b/Tests/Parser/Client/LibraryTest.php
index a9baa68ee3..017a4f47ce 100644
--- a/Tests/Parser/Client/LibraryTest.php
+++ b/Tests/Parser/Client/LibraryTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Client;
 
 use DeviceDetector\Parser\Client\Library;
@@ -21,7 +19,7 @@ class LibraryTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $client): void
+    public function testParse($useragent, array $client)
     {
         $libraryParser = new Library();
         $libraryParser->setVersionTruncation(Library::VERSION_TRUNCATION_NONE);
@@ -29,14 +27,14 @@ public function testParse(string $useragent, array $client): void
         $this->assertEquals($client, $libraryParser->parse());
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/library.yml');
 
         return $fixtureData;
     }
 
-    public function testStructureLibraryYml(): void
+    public function testStructureLibraryYml()
     {
         $ymlDataItems = Spyc::YAMLLoad(__DIR__ . '/../../../regexes/client/libraries.yml');
 
@@ -44,9 +42,9 @@ public function testStructureLibraryYml(): void
             $this->assertTrue(\array_key_exists('regex', $item), 'key "regex" not exist');
             $this->assertTrue(\array_key_exists('name', $item), 'key "name" not exist');
             $this->assertTrue(\array_key_exists('version', $item), 'key "version" not exist');
-            $this->assertIsString($item['regex']);
-            $this->assertIsString($item['name']);
-            $this->assertIsString($item['version']);
+            $this->assertNotNull($item['regex']);
+            $this->assertNotNull($item['name']);
+            $this->assertNotNull($item['version']);
         }
     }
 }
diff --git a/Tests/Parser/Client/MediaPlayerTest.php b/Tests/Parser/Client/MediaPlayerTest.php
index b8ca8482ea..578ac030a7 100644
--- a/Tests/Parser/Client/MediaPlayerTest.php
+++ b/Tests/Parser/Client/MediaPlayerTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Client;
 
 use DeviceDetector\Parser\Client\MediaPlayer;
@@ -21,7 +19,7 @@ class MediaPlayerTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $client): void
+    public function testParse($useragent, array $client)
     {
         $mediaPlayerParser = new MediaPlayer();
         $mediaPlayerParser->setVersionTruncation(MediaPlayer::VERSION_TRUNCATION_NONE);
@@ -29,14 +27,14 @@ public function testParse(string $useragent, array $client): void
         $this->assertEquals($client, $mediaPlayerParser->parse());
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/mediaplayer.yml');
 
         return $fixtureData;
     }
 
-    public function testStructureMediaPlayerYml(): void
+    public function testStructureMediaPlayerYml()
     {
         $ymlDataItems = Spyc::YAMLLoad(__DIR__ . '/../../../regexes/client/mediaplayers.yml');
 
@@ -44,9 +42,9 @@ public function testStructureMediaPlayerYml(): void
             $this->assertTrue(\array_key_exists('regex', $item), 'key "regex" not exist');
             $this->assertTrue(\array_key_exists('name', $item), 'key "name" not exist');
             $this->assertTrue(\array_key_exists('version', $item), 'key "version" not exist');
-            $this->assertIsString($item['regex']);
-            $this->assertIsString($item['name']);
-            $this->assertIsString($item['version']);
+            $this->assertNotNull($item['regex']);
+            $this->assertNotNull($item['name']);
+            $this->assertNotNull($item['version']);
         }
     }
 }
diff --git a/Tests/Parser/Client/MobileAppTest.php b/Tests/Parser/Client/MobileAppTest.php
index c15da0f6a2..8ac73184cb 100644
--- a/Tests/Parser/Client/MobileAppTest.php
+++ b/Tests/Parser/Client/MobileAppTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Client;
 
 use DeviceDetector\Parser\Client\MobileApp;
@@ -21,7 +19,7 @@ class MobileAppTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $client): void
+    public function testParse($useragent, array $client)
     {
         $mobileAppParser = new MobileApp();
         $mobileAppParser->setVersionTruncation(MobileApp::VERSION_TRUNCATION_NONE);
@@ -29,14 +27,14 @@ public function testParse(string $useragent, array $client): void
         $this->assertEquals($client, $mobileAppParser->parse());
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/mobile_app.yml');
 
         return $fixtureData;
     }
 
-    public function testStructureMobileAppYml(): void
+    public function testStructureMobileAppYml()
     {
         $ymlDataItems = Spyc::YAMLLoad(__DIR__ . '/../../../regexes/client/mobile_apps.yml');
 
diff --git a/Tests/Parser/Client/PIMTest.php b/Tests/Parser/Client/PIMTest.php
index 27a389143c..209f5077e7 100644
--- a/Tests/Parser/Client/PIMTest.php
+++ b/Tests/Parser/Client/PIMTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Client;
 
 use DeviceDetector\Parser\Client\PIM;
@@ -21,7 +19,7 @@ class PIMTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $client): void
+    public function testParse($useragent, array $client)
     {
         $PIMParser = new PIM();
         $PIMParser->setVersionTruncation(PIM::VERSION_TRUNCATION_NONE);
@@ -29,14 +27,14 @@ public function testParse(string $useragent, array $client): void
         $this->assertEquals($client, $PIMParser->parse());
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/pim.yml');
 
         return $fixtureData;
     }
 
-    public function testStructurePimYml(): void
+    public function testStructurePimYml()
     {
         $ymlDataItems = Spyc::YAMLLoad(__DIR__ . '/../../../regexes/client/pim.yml');
 
@@ -44,9 +42,9 @@ public function testStructurePimYml(): void
             $this->assertTrue(\array_key_exists('regex', $item), 'key "regex" not exist');
             $this->assertTrue(\array_key_exists('name', $item), 'key "name" not exist');
             $this->assertTrue(\array_key_exists('version', $item), 'key "version" not exist');
-            $this->assertIsString($item['regex']);
-            $this->assertIsString($item['name']);
-            $this->assertIsString($item['version']);
+            $this->assertNotNull($item['regex']);
+            $this->assertNotNull($item['name']);
+            $this->assertNotNull($item['version']);
         }
     }
 }
diff --git a/Tests/Parser/Device/CameraTest.php b/Tests/Parser/Device/CameraTest.php
index c429fe2bb6..d6dfe48265 100644
--- a/Tests/Parser/Device/CameraTest.php
+++ b/Tests/Parser/Device/CameraTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Device;
 
 use DeviceDetector\Parser\Device\Camera;
@@ -21,7 +19,7 @@ class CameraTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $device): void
+    public function testParse($useragent, array $device)
     {
         $consoleParser = new Camera();
         $consoleParser->setUserAgent($useragent);
@@ -31,7 +29,7 @@ public function testParse(string $useragent, array $device): void
         $this->assertEquals($device['model'], $consoleParser->getModel());
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/camera.yml');
 
diff --git a/Tests/Parser/Device/CarBrowserTest.php b/Tests/Parser/Device/CarBrowserTest.php
index 2758e07dd1..fa02486906 100644
--- a/Tests/Parser/Device/CarBrowserTest.php
+++ b/Tests/Parser/Device/CarBrowserTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Device;
 
 use DeviceDetector\Parser\Device\CarBrowser;
@@ -21,7 +19,7 @@ class CarBrowserTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $device): void
+    public function testParse($useragent, array $device)
     {
         $consoleParser = new CarBrowser();
         $consoleParser->setUserAgent($useragent);
@@ -31,7 +29,7 @@ public function testParse(string $useragent, array $device): void
         $this->assertEquals($device['model'], $consoleParser->getModel());
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/car_browser.yml');
 
diff --git a/Tests/Parser/Device/ConsoleTest.php b/Tests/Parser/Device/ConsoleTest.php
index 83c4593978..6858c2a4f1 100644
--- a/Tests/Parser/Device/ConsoleTest.php
+++ b/Tests/Parser/Device/ConsoleTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Device;
 
 use DeviceDetector\Parser\Device\Console;
@@ -21,7 +19,7 @@ class ConsoleTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $device): void
+    public function testParse($useragent, array $device)
     {
         $consoleParser = new Console();
         $consoleParser->setUserAgent($useragent);
@@ -31,7 +29,7 @@ public function testParse(string $useragent, array $device): void
         $this->assertEquals($device['model'], $consoleParser->getModel());
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/console.yml');
 
diff --git a/Tests/Parser/Device/DeviceParserAbstractTest.php b/Tests/Parser/Device/DeviceParserAbstractTest.php
index a244182043..681fed1ba8 100644
--- a/Tests/Parser/Device/DeviceParserAbstractTest.php
+++ b/Tests/Parser/Device/DeviceParserAbstractTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Device;
 
 use DeviceDetector\Parser\Device\AbstractDeviceParser;
@@ -17,21 +15,21 @@
 
 class DeviceParserAbstractTest extends TestCase
 {
-    public function testGetAvailableDeviceTypes(): void
+    public function testGetAvailableDeviceTypes()
     {
         $available = AbstractDeviceParser::getAvailableDeviceTypes();
         $this->assertGreaterThan(5, \count($available));
         $this->assertContains('desktop', \array_keys($available));
     }
 
-    public function testGetAvailableDeviceTypeNames(): void
+    public function testGetAvailableDeviceTypeNames()
     {
         $available = AbstractDeviceParser::getAvailableDeviceTypeNames();
         $this->assertGreaterThan(5, \count($available));
         $this->assertContains('desktop', $available);
     }
 
-    public function testGetFullName(): void
+    public function testGetFullName()
     {
         $this->assertEquals('', AbstractDeviceParser::getFullName('Invalid'));
         $this->assertEquals('Asus', AbstractDeviceParser::getFullName('AU'));
diff --git a/Tests/Parser/Device/HbbTvTest.php b/Tests/Parser/Device/HbbTvTest.php
index 0d640ce669..460a2e2217 100644
--- a/Tests/Parser/Device/HbbTvTest.php
+++ b/Tests/Parser/Device/HbbTvTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Device;
 
 use DeviceDetector\Parser\Device\HbbTv;
@@ -17,7 +15,7 @@
 
 class HbbTvTest extends TestCase
 {
-    public function testIsHbbTv(): void
+    public function testIsHbbTv()
     {
         $hbbTvParser = new HbbTv();
         $hbbTvParser->setUserAgent('Opera/9.80 (Linux mips ; U; HbbTV/1.1.1 (; Philips; ; ; ; ) CE-HTML/1.0 NETTV/3.2.1; en) Presto/2.6.33 Version/10.70');
diff --git a/Tests/Parser/Device/NotebookTest.php b/Tests/Parser/Device/NotebookTest.php
index 9801229341..e121fa9044 100644
--- a/Tests/Parser/Device/NotebookTest.php
+++ b/Tests/Parser/Device/NotebookTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Device;
 
 use DeviceDetector\Parser\Device\Notebook;
@@ -21,7 +19,7 @@ class NotebookTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $device): void
+    public function testParse($useragent, array $device)
     {
         $notebookParser = new Notebook();
         $notebookParser->setUserAgent($useragent);
@@ -31,7 +29,7 @@ public function testParse(string $useragent, array $device): void
         $this->assertEquals($device['model'], $notebookParser->getModel());
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/notebook.yml');
 
diff --git a/Tests/Parser/Device/ShellTvTest.php b/Tests/Parser/Device/ShellTvTest.php
index db71ea0b10..012b5bb58e 100644
--- a/Tests/Parser/Device/ShellTvTest.php
+++ b/Tests/Parser/Device/ShellTvTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser\Device;
 
 use DeviceDetector\Parser\Device\ShellTv;
@@ -17,7 +15,7 @@
 
 class ShellTvTest extends TestCase
 {
-    public function testIsShellTv(): void
+    public function testIsShellTv()
     {
         $dd = new ShellTv();
         $dd->setUserAgent('Leff Shell LC390TA2A');
diff --git a/Tests/Parser/OperatingSystemTest.php b/Tests/Parser/OperatingSystemTest.php
index e68a2609a4..c30299ed63 100644
--- a/Tests/Parser/OperatingSystemTest.php
+++ b/Tests/Parser/OperatingSystemTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser;
 
 use DeviceDetector\ClientHints;
@@ -24,7 +22,7 @@ class OperatingSystemTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, array $os, ?array $headers = null): void
+    public function testParse($useragent, array $os, $headers = null)
     {
         $osParser = new OperatingSystem();
         $osParser->setUserAgent($useragent);
@@ -37,7 +35,7 @@ public function testParse(string $useragent, array $os, ?array $headers = null):
         self::$osTested[] = $os['name'];
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/oss.yml');
 
@@ -47,13 +45,13 @@ public function getFixtures(): array
     /**
      * @dataProvider getAllOs
      */
-    public function testOSInGroup(string $os): void
+    public function testOSInGroup($os)
     {
         $familyOs = \call_user_func_array('array_merge', \array_values(OperatingSystem::getAvailableOperatingSystemFamilies()));
         $this->assertContains($os, $familyOs);
     }
 
-    public function getAllOs(): array
+    public function getAllOs()
     {
         $allOs = \array_keys(OperatingSystem::getAvailableOperatingSystems());
         $allOs = \array_map(static function ($os) {
@@ -66,13 +64,13 @@ public function getAllOs(): array
     /**
      * @dataProvider getAllFamilyOs
      */
-    public function testFamilyOSExists(string $os): void
+    public function testFamilyOSExists($os)
     {
         $allOs = \array_keys(OperatingSystem::getAvailableOperatingSystems());
         $this->assertContains($os, $allOs);
     }
 
-    public function getAllFamilyOs(): array
+    public function getAllFamilyOs()
     {
         $allFamilyOs = \call_user_func_array('array_merge', \array_values(OperatingSystem::getAvailableOperatingSystemFamilies()));
         $allFamilyOs = \array_map(static function ($os) {
@@ -82,7 +80,7 @@ public function getAllFamilyOs(): array
         return $allFamilyOs;
     }
 
-    public function testGetAvailableOperatingSystems(): void
+    public function testGetAvailableOperatingSystems()
     {
         $this->assertGreaterThan(70, OperatingSystem::getAvailableOperatingSystems());
     }
@@ -90,12 +88,12 @@ public function testGetAvailableOperatingSystems(): void
     /**
      * @dataProvider getNameFromIds
      */
-    public function testGetNameFromId(string $os, string $version, ?string $expected): void
+    public function testGetNameFromId($os, $version, $expected)
     {
         $this->assertEquals($expected, OperatingSystem::getNameFromId($os, $version));
     }
 
-    public function getNameFromIds(): array
+    public function getNameFromIds()
     {
         return [
             ['DEB', '4.5', 'Debian 4.5'],
@@ -105,7 +103,7 @@ public function getNameFromIds(): array
         ];
     }
 
-    public function testAllOperatingSystemsTested(): void
+    public function testAllOperatingSystemsTested()
     {
         $allBrowsers = OperatingSystem::getAvailableOperatingSystems();
         $osNotTested = \array_diff($allBrowsers, self::$osTested);
diff --git a/Tests/Parser/VendorFragmentTest.php b/Tests/Parser/VendorFragmentTest.php
index fbeb7af4c4..0e95063753 100644
--- a/Tests/Parser/VendorFragmentTest.php
+++ b/Tests/Parser/VendorFragmentTest.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Tests\Parser;
 
 use DeviceDetector\Parser\VendorFragment;
@@ -23,7 +21,7 @@ class VendorFragmentTest extends TestCase
     /**
      * @dataProvider getFixtures
      */
-    public function testParse(string $useragent, string $vendor): void
+    public function testParse($useragent, $vendor)
     {
         $vfParser = new VendorFragment();
         $vfParser->setUserAgent($useragent);
@@ -31,14 +29,14 @@ public function testParse(string $useragent, string $vendor): void
         self::$regexesTested[] = $vfParser->getMatchedRegex();
     }
 
-    public function getFixtures(): array
+    public function getFixtures()
     {
         $fixtureData = Spyc::YAMLLoad(\realpath(__DIR__) . '/fixtures/vendorfragments.yml');
 
         return $fixtureData;
     }
 
-    public function testAllRegexesTested(): void
+    public function testAllRegexesTested()
     {
         $regexesNotTested = [];
 
diff --git a/Yaml/ParserInterface.php b/Yaml/ParserInterface.php
index e3aa2f017a..4581e99d6b 100644
--- a/Yaml/ParserInterface.php
+++ b/Yaml/ParserInterface.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Yaml;
 
 interface ParserInterface
@@ -21,5 +19,5 @@ interface ParserInterface
      *
      * @return mixed
      */
-    public function parseFile(string $file);
+    public function parseFile($file);
 }
diff --git a/Yaml/Pecl.php b/Yaml/Pecl.php
index ba30efb11b..5acaad96dd 100644
--- a/Yaml/Pecl.php
+++ b/Yaml/Pecl.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Yaml;
 
 use Exception;
@@ -31,7 +29,7 @@ class Pecl implements ParserInterface
      *
      * @throws Exception If the YAML extension is not installed
      */
-    public function parseFile(string $file)
+    public function parseFile($file)
     {
         if (false === \function_exists('yaml_parse_file')) {
             throw new Exception('Pecl YAML extension is not installed');
diff --git a/Yaml/Spyc.php b/Yaml/Spyc.php
index 24d0110b0a..eb3c1ba3b9 100644
--- a/Yaml/Spyc.php
+++ b/Yaml/Spyc.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Yaml;
 
 use Spyc as SpycParser;
@@ -23,7 +21,7 @@ class Spyc implements ParserInterface
      *
      * @return mixed
      */
-    public function parseFile(string $file)
+    public function parseFile($file)
     {
         return SpycParser::YAMLLoad($file);
     }
diff --git a/Yaml/Symfony.php b/Yaml/Symfony.php
index 00bd6917d4..1592ec97f8 100644
--- a/Yaml/Symfony.php
+++ b/Yaml/Symfony.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 namespace DeviceDetector\Yaml;
 
 use Symfony\Component\Yaml\Yaml;
@@ -23,7 +21,7 @@ class Symfony implements ParserInterface
      *
      * @return mixed
      */
-    public function parseFile(string $file)
+    public function parseFile($file)
     {
         return Yaml::parseFile($file);
     }
diff --git a/autoload.php b/autoload.php
index 34acb171d3..44fd205041 100644
--- a/autoload.php
+++ b/autoload.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 /**
  * PSR-4 autoloader implementation for the DeviceDetector namespace.
  * First we define the 'dd_autoload' function, and then we register
@@ -16,7 +14,7 @@
  *
  * @return void
  */
-function dd_autoload(string $class): void
+function dd_autoload($class)
 {
     if (false === strpos($class, 'DeviceDetector\\')) {
         return;
diff --git a/composer.json b/composer.json
index 46d7dda060..30ec0aacf1 100644
--- a/composer.json
+++ b/composer.json
@@ -23,17 +23,16 @@
         "exclude-from-classmap": ["Tests/"]
     },
     "require": {
-        "php": "^7.2|^8.0",
+        "php": ">=5.6.0",
         "mustangostang/spyc": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.5.8",
+        "phpunit/phpunit": "^5.7.0",
         "psr/cache": "^1.0.1",
         "psr/simple-cache": "^1.0.1",
         "matthiasmullie/scrapbook": "^1.4.7",
-        "phpstan/phpstan": "^1.10.44",
-        "mayflower/mo4-coding-standard": "^v9.0.0",
-        "symfony/yaml": "^5.1.7"
+        "mayflower/mo4-coding-standard": "^v2.0.0",
+        "symfony/yaml": "^3.0.0"
     },
     "suggest": {
         "doctrine/cache": "Can directly be used for caching purpose",
diff --git a/misc/fileTest.php b/misc/fileTest.php
index f1820ba200..3d7d00b334 100644
--- a/misc/fileTest.php
+++ b/misc/fileTest.php
@@ -25,8 +25,6 @@
  * `php file-test.php /tmp/source-useragent.txt "not" "useragent" > /tmp/useragent-not-detected.txt`
  */
 
-declare(strict_types=1);
-
 use DeviceDetector\DeviceDetector;
 use DeviceDetector\Parser\Device\AbstractDeviceParser;
 
@@ -48,11 +46,11 @@
 define('REPORT_TYPE_YML', 'yml');
 define('REPORT_TYPE_USERAGENT', 'useragent');
 
-$file       = $argv[1] ?? '';
-$showMode   = $argv[2] ?? 'not';
-$reportMode = $argv[3] ?? 'yml';
+$file       = isset($argv[1]) ? $argv[1] : '';
+$showMode   = isset($argv[2]) ? $argv[2] : 'not';
+$reportMode = isset($argv[3]) ? $argv[3] : 'yml';
 
-function printHelpAndExit(): void
+function printHelpAndExit()
 {
     echo "Usage command:\n";
     echo "php file-test.php <patch to file> <detect mode> <report mode> > report.txt\n\n";
@@ -75,7 +73,7 @@ function printHelpAndExit(): void
  * @param array $result
  * @param string $format
  */
-function printReport(array $result, string $format): void
+function printReport(array $result, $format)
 {
     if (REPORT_TYPE_YML === $format) {
         echo Spyc::YAMLDump($result, 2, 0);
diff --git a/misc/generateBrandIdFree.php b/misc/generateBrandIdFree.php
index cfdbd92a7a..28025e3cd8 100644
--- a/misc/generateBrandIdFree.php
+++ b/misc/generateBrandIdFree.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 require __DIR__ . '/../vendor/autoload.php';
 
 use DeviceDetector\Parser\Client\Browser;
@@ -32,7 +30,7 @@
 $browserExistIds = array_keys(Browser::getAvailableBrowsers());
 $browserFreeIds  = array_diff($mapIds, $browserExistIds);
 
-function pettyTable(array $data): string
+function pettyTable(array $data)
 {
     $columns = [];
 
diff --git a/misc/rewriteTestFixtureFiles.php b/misc/rewriteTestFixtureFiles.php
index d70d394592..ad8e890e55 100644
--- a/misc/rewriteTestFixtureFiles.php
+++ b/misc/rewriteTestFixtureFiles.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 use DeviceDetector\DeviceDetector;
 use DeviceDetector\Parser\AbstractParser;
 
diff --git a/misc/sortTestFixtureFiles.php b/misc/sortTestFixtureFiles.php
index a5c4fa7936..ce646037ca 100644
--- a/misc/sortTestFixtureFiles.php
+++ b/misc/sortTestFixtureFiles.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 use DeviceDetector\DeviceDetector;
 use DeviceDetector\Parser\AbstractParser;
 use DeviceDetector\Parser\Device\AbstractDeviceParser;
@@ -52,22 +50,22 @@
                                 return strtolower($a['user_agent']) < strtolower($b['user_agent']) ? -1 : 1;
                             }
 
-                            return ($a['client']['version'] ?? '') < ($b['client']['version'] ?? '') ? -1 : 1;
+                            return (isset($a['client']['version']) ? $a['client']['version'] : '') < (isset($b['client']['version']) ? $b['client']['version'] : '') ? -1 : 1;
                         }
 
-                        return ($a['client']['name'] ?? '') < ($b['client']['name'] ?? '') ? -1 : 1;
+                        return (isset($a['client']['name']) ? $a['client']['name'] : '') < (isset($b['client']['name']) ? $b['client']['name'] : '') ? -1 : 1;
                     }
 
-                    return ($a['os']['version'] ?? '') < ($b['os']['version'] ?? '') ? -1 : 1;
+                    return (isset($a['os']['version']) ? $a['os']['version'] : '') < (isset($b['os']['version']) ? $b['os']['version'] : '') ? -1 : 1;
                 }
 
-                return ($a['os']['name'] ?? '') < ($b['os']['name'] ?? '') ? -1 : 1;
+                return (isset($a['os']['name']) ? $a['os']['name'] : '') < (isset($b['os']['name']) ? $b['os']['name'] : '') ? -1 : 1;
             }
 
-            return ($a['device']['model'] ?? '') < ($b['device']['model'] ?? '') ? -1 : 1;
+            return (isset($a['device']['model']) ? $a['device']['model'] : '') < (isset($b['device']['model']) ? $b['device']['model'] : '') ? -1 : 1;
         }
 
-        return ($a['device']['brand'] ?? '') < ($b['device']['brand'] ?? '') ? -1 : 1;
+        return (isset($a['device']['brand']) ? $a['device']['brand'] : '') < (isset($b['device']['brand']) ? $b['device']['brand'] : '') ? -1 : 1;
     });
 
     $chunks = array_chunk($fixtures, 500);
diff --git a/misc/statistics.php b/misc/statistics.php
index eac5fd92de..8d41f1f5b7 100644
--- a/misc/statistics.php
+++ b/misc/statistics.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 use DeviceDetector\DeviceDetector;
 use DeviceDetector\Parser\Device\AbstractDeviceParser;
 
@@ -76,7 +74,7 @@
 
 $timeElapsed = microtime(true) - $startTime;
 
-function getPercentage(int $cur, int $max): string
+function getPercentage($cur, $max)
 {
     return format((int) round($cur * 100 / $max), '   ');
 }
@@ -86,7 +84,7 @@ function getPercentage(int $cur, int $max): string
  * @param int|string $length
  * @return string
  */
-function format($str, $length): string
+function format($str, $length)
 {
     return sprintf('%' . strlen((string) $length) . 'd', $str);
 }
diff --git a/misc/test.php b/misc/test.php
index fce4355d20..4f5c930d9c 100644
--- a/misc/test.php
+++ b/misc/test.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 require __DIR__ . '/../vendor/autoload.php';
 
 use DeviceDetector\DeviceDetector;
@@ -20,7 +18,7 @@
         $userAgent = $argv[1];
     }
 } else {
-    $userAgent = $_GET['ua'] ?? $_SERVER['HTTP_USER_AGENT'];
+    $userAgent = isset($_GET['ua']) ? $_GET['ua'] : $_SERVER['HTTP_USER_AGENT'];
 }
 
 AbstractDeviceParser::setVersionTruncation(AbstractDeviceParser::VERSION_TRUNCATION_NONE);
diff --git a/misc/updateReadme.php b/misc/updateReadme.php
index dd10ef1b98..a008e1104a 100644
--- a/misc/updateReadme.php
+++ b/misc/updateReadme.php
@@ -8,8 +8,6 @@
  * @license http://www.gnu.org/licenses/lgpl.html LGPL v3 or later
  */
 
-declare(strict_types=1);
-
 use DeviceDetector\Parser\Client\Browser;
 use DeviceDetector\Parser\Client\Browser\Engine;
 use DeviceDetector\Parser\Client\FeedReader;
diff --git a/phpstan.neon b/phpstan.neon
deleted file mode 100644
index 124fb0123a..0000000000
--- a/phpstan.neon
+++ /dev/null
@@ -1,16 +0,0 @@
-parameters:
-    level: max
-    bootstrapFiles:
-        - %rootDir%/../../autoload.php
-    paths:
-        - %rootDir%/../../../
-    excludePaths:
-        - %rootDir%/../../../vendor
-        - %rootDir%/../../../misc
-        - %rootDir%/../../../Tests
-        - %rootDir%/../../../autoload.php
-    ignoreErrors:
-        - '#.+Doctrine\\Common\\Cache\\CacheProvider.+#'
-        - '#.+unknown class Illuminate\\Support\\Facades\\Cache.+#'
-    reportUnmatchedIgnoredErrors: false
-    checkMissingIterableValueType: false
\ No newline at end of file