diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b6de16f7..9c1509fd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,7 +10,7 @@ jobs:
     strategy:
       max-parallel: 10
       matrix:
-        php: ['7.2', '7.3', '7.4']
+        php: ['7.2', '7.3', '7.4', '8.0']
         sf_version: ['3.4.*', '4.4.*', '5.0.*']
 
     steps:
@@ -103,7 +103,7 @@ jobs:
       - name: Set up PHP
         uses: shivammathur/setup-php@2.1.0
         with:
-          php-version: 7.3
+          php-version: 7.4
           tools: flex
 
       - name: Checkout code
@@ -122,7 +122,7 @@ jobs:
 
       - name: Run tests
         run: |
-          docker run --rm --net buzz-bridge -v "$PWD":/usr/src/myapp -w /usr/src/myapp -e BUZZ_TEST_SERVER=http://test-server/index.php tommymuehle/docker-alpine-php-nightly php vendor/bin/phpunit
+          docker run --rm --net buzz-bridge -v "$PWD":/usr/src/myapp -w /usr/src/myapp -e BUZZ_TEST_SERVER=http://test-server/index.php php:7.4-cli php vendor/bin/phpunit
 
   lowest:
     name: Lowest deps
diff --git a/.github/workflows/static.yml b/.github/workflows/static.yml
index 321ff23c..70145885 100644
--- a/.github/workflows/static.yml
+++ b/.github/workflows/static.yml
@@ -42,6 +42,6 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Psalm
-        uses: docker://muglug/psalm-github-actions
+        uses: docker://vimeo/psalm-github-actions
         with:
           args: --no-progress --show-info=false --stats
diff --git a/Dockerfile b/Dockerfile
index 5f26f56b..d99f8cbf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM php:7.3-fpm-stretch
+FROM php:7.4-fpm-buster
 
 # Install Nginx
 RUN apt-get update -qq && apt-get install -y --no-install-recommends -qq nginx
diff --git a/composer.json b/composer.json
index 6c478fc0..3843c04f 100644
--- a/composer.json
+++ b/composer.json
@@ -18,7 +18,7 @@
         }
     ],
     "require": {
-        "php": "^7.1",
+        "php": "^7.1 || ^8.0",
         "psr/http-message": "^1.0",
         "psr/http-client": "^1.0",
         "php-http/httplug": "^1.1 || ^2.0",
@@ -26,10 +26,10 @@
         "psr/http-factory": "^1.0"
     },
     "require-dev": {
-        "php-http/client-integration-tests": "^2.0.1",
+        "php-http/client-integration-tests": "^3.0",
         "nyholm/psr7": "^1.0",
         "psr/log": "^1.0",
-        "phpunit/phpunit": "7.5.20"
+        "phpunit/phpunit": "^7.5 || ^9.4"
     },
     "provide": {
         "php-http/client-implementation": "1.0",
diff --git a/lib/Client/AbstractClient.php b/lib/Client/AbstractClient.php
index 50cc5852..e63abb9a 100644
--- a/lib/Client/AbstractClient.php
+++ b/lib/Client/AbstractClient.php
@@ -13,7 +13,7 @@
 abstract class AbstractClient
 {
     /**
-     * @var OptionsResolver
+     * @var OptionsResolver|null
      */
     private $optionsResolver;
 
diff --git a/lib/Client/MultiCurl.php b/lib/Client/MultiCurl.php
index c8e04e88..01785b55 100644
--- a/lib/Client/MultiCurl.php
+++ b/lib/Client/MultiCurl.php
@@ -56,7 +56,13 @@ public function __construct($responseFactory, array $options = [])
     {
         parent::__construct($responseFactory, $options);
 
-        if (\PHP_VERSION_ID < 70215 || \PHP_VERSION_ID === 70300 || \PHP_VERSION_ID === 70301 || !(CURL_VERSION_HTTP2 & curl_version()['features'])) {
+        if (
+            \PHP_VERSION_ID < 70215 ||
+            \PHP_VERSION_ID === 70300 ||
+            \PHP_VERSION_ID === 70301 ||
+            \PHP_VERSION_ID >= 80000 ||
+            !(CURL_VERSION_HTTP2 & curl_version()['features'])
+        ) {
             // Dont use HTTP/2 push when it's unsupported or buggy, see https://bugs.php.net/76675
             $this->serverPushSupported = false;
         }
diff --git a/tests/Integration/BaseIntegrationTest.php b/tests/Integration/BaseIntegrationTest.php
index a71cbf6e..9a4fab01 100644
--- a/tests/Integration/BaseIntegrationTest.php
+++ b/tests/Integration/BaseIntegrationTest.php
@@ -8,7 +8,7 @@
 
 abstract class BaseIntegrationTest extends TestCase
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         if (getenv('BUZZ_TEST_SERVER')) {
diff --git a/tests/Integration/BuzzIntegrationTest.php b/tests/Integration/BuzzIntegrationTest.php
index 2f937c43..902732b5 100644
--- a/tests/Integration/BuzzIntegrationTest.php
+++ b/tests/Integration/BuzzIntegrationTest.php
@@ -21,7 +21,7 @@
 
 class BuzzIntegrationTest extends BaseIntegrationTest
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         if (empty($_SERVER['BUZZ_TEST_SERVER'])) {
@@ -125,7 +125,7 @@ public function testFormPostWithRequestBuilder($client, $async)
         $this->assertNotEmpty($response->getBody()->__toString(), 'Response from server should not be empty');
 
         $data = json_decode($response->getBody()->__toString(), true);
-        $this->assertInternalType('array', $data, $response->getBody()->__toString());
+        $this->assertIsArray($data, $response->getBody()->__toString());
         $this->assertArrayHasKey('SERVER', $data);
 
         $this->assertStringStartsWith('multipart/form-data', $data['SERVER']['CONTENT_TYPE']);
@@ -156,7 +156,7 @@ public function testFormPostWithLargeRequestBody($client, $async)
         $this->assertNotEmpty($response->getBody()->__toString(), 'Response from server should not be empty');
 
         $data = json_decode($response->getBody()->__toString(), true);
-        $this->assertInternalType('array', $data, $response->getBody()->__toString());
+        $this->assertIsArray($data, $response->getBody()->__toString());
         $this->assertArrayHasKey('SERVER', $data);
 
         $this->assertStringStartsWith('multipart/form-data', $data['SERVER']['CONTENT_TYPE']);
diff --git a/tests/Integration/Httplug/BaseIntegrationTest.php b/tests/Integration/Httplug/BaseIntegrationTest.php
index 55e1fb95..38c9a8bd 100644
--- a/tests/Integration/Httplug/BaseIntegrationTest.php
+++ b/tests/Integration/Httplug/BaseIntegrationTest.php
@@ -9,7 +9,7 @@
 
 abstract class BaseIntegrationTest extends HttpClientTest
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         if (false === PHPUnitUtility::getUri()) {
diff --git a/tests/Integration/Httplug/BrowserIntegrationTest.php b/tests/Integration/Httplug/BrowserIntegrationTest.php
index 54ac90c0..661cf082 100644
--- a/tests/Integration/Httplug/BrowserIntegrationTest.php
+++ b/tests/Integration/Httplug/BrowserIntegrationTest.php
@@ -7,10 +7,11 @@
 use Buzz\Browser;
 use Buzz\Client\FileGetContents;
 use Nyholm\Psr7\Factory\Psr17Factory;
+use Psr\Http\Client\ClientInterface;
 
 class BrowserIntegrationTest extends BaseIntegrationTest
 {
-    protected function createHttpAdapter()
+    protected function createHttpAdapter(): ClientInterface
     {
         $client = new FileGetContents(new Psr17Factory(), []);
         $browser = new Browser($client, new Psr17Factory());
diff --git a/tests/Integration/Httplug/CurlIntegrationTest.php b/tests/Integration/Httplug/CurlIntegrationTest.php
index c43f7cdf..5ee7fdbc 100644
--- a/tests/Integration/Httplug/CurlIntegrationTest.php
+++ b/tests/Integration/Httplug/CurlIntegrationTest.php
@@ -6,10 +6,11 @@
 
 use Buzz\Client\Curl;
 use Nyholm\Psr7\Factory\Psr17Factory;
+use Psr\Http\Client\ClientInterface;
 
 class CurlIntegrationTest extends BaseIntegrationTest
 {
-    protected function createHttpAdapter()
+    protected function createHttpAdapter(): ClientInterface
     {
         return new Curl(new Psr17Factory(), []);
     }
diff --git a/tests/Integration/Httplug/FileGetContentsIntegrationTest.php b/tests/Integration/Httplug/FileGetContentsIntegrationTest.php
index d1740c1c..00bd80f8 100644
--- a/tests/Integration/Httplug/FileGetContentsIntegrationTest.php
+++ b/tests/Integration/Httplug/FileGetContentsIntegrationTest.php
@@ -6,10 +6,11 @@
 
 use Buzz\Client\FileGetContents;
 use Nyholm\Psr7\Factory\Psr17Factory;
+use Psr\Http\Client\ClientInterface;
 
 class FileGetContentsIntegrationTest extends BaseIntegrationTest
 {
-    protected function createHttpAdapter()
+    protected function createHttpAdapter(): ClientInterface
     {
         return new FileGetContents(new Psr17Factory(), []);
     }
diff --git a/tests/Integration/Httplug/MultiCurlIntegrationTest.php b/tests/Integration/Httplug/MultiCurlIntegrationTest.php
index 324ff087..ecdfa407 100644
--- a/tests/Integration/Httplug/MultiCurlIntegrationTest.php
+++ b/tests/Integration/Httplug/MultiCurlIntegrationTest.php
@@ -6,10 +6,11 @@
 
 use Buzz\Client\MultiCurl;
 use Nyholm\Psr7\Factory\Psr17Factory;
+use Psr\Http\Client\ClientInterface;
 
 class MultiCurlIntegrationTest extends BaseIntegrationTest
 {
-    protected function createHttpAdapter()
+    protected function createHttpAdapter(): ClientInterface
     {
         return new MultiCurl(new Psr17Factory(), []);
     }
diff --git a/tests/Integration/MultiCurlServerPushTest.php b/tests/Integration/MultiCurlServerPushTest.php
index 5f3257a8..0d386423 100644
--- a/tests/Integration/MultiCurlServerPushTest.php
+++ b/tests/Integration/MultiCurlServerPushTest.php
@@ -10,10 +10,10 @@
 
 class MultiCurlServerPushTest extends BaseIntegrationTest
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
-        if (\PHP_VERSION_ID < 70400 || curl_version()['version_number'] < 472065) {
+        if (\PHP_VERSION_ID < 70400 || \PHP_VERSION_ID >= 80000 || curl_version()['version_number'] < 472065) {
             $this->markTestSkipped('This environment does not support server push');
         }
     }
diff --git a/tests/Integration/MultiCurlTest.php b/tests/Integration/MultiCurlTest.php
index 776cdb54..35723531 100644
--- a/tests/Integration/MultiCurlTest.php
+++ b/tests/Integration/MultiCurlTest.php
@@ -11,7 +11,7 @@
 
 class MultiCurlTest extends BaseIntegrationTest
 {
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         if (empty($_SERVER['BUZZ_TEST_SERVER'])) {
diff --git a/tests/Unit/BrowserTest.php b/tests/Unit/BrowserTest.php
index f9702c1e..83eec31b 100644
--- a/tests/Unit/BrowserTest.php
+++ b/tests/Unit/BrowserTest.php
@@ -20,7 +20,7 @@ class BrowserTest extends TestCase
     /** @var Browser */
     private $browser;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->client = $this->getMockBuilder('Buzz\Client\Curl')
             ->disableOriginalConstructor()
@@ -112,7 +112,7 @@ public function testSubmitForm(array $fields, array $headers, array $requestHead
             $regex = substr($requestBody, 5);
             $regex = str_replace("\n", "\r\n", $regex);
 
-            return preg_match($regex, $input);
+            return false !== preg_match($regex, $input);
         };
 
         $browser = $this->getMockBuilder(Browser::class)
diff --git a/tests/Unit/Middleware/History/JournalTest.php b/tests/Unit/Middleware/History/JournalTest.php
index 8b88f39a..bc2c865e 100644
--- a/tests/Unit/Middleware/History/JournalTest.php
+++ b/tests/Unit/Middleware/History/JournalTest.php
@@ -23,7 +23,7 @@ class JournalTest extends TestCase
 
     protected $response3;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->request1 = new Request('GET', '/r1', [], 'request1');
         $this->request2 = new Request('GET', '/r2', [], 'request2');
@@ -33,7 +33,7 @@ protected function setUp()
         $this->response3 = new Response(200, [], 'response3');
     }
 
-    protected function tearDown()
+    protected function tearDown(): void
     {
         $this->request1 = null;
         $this->request2 = null;
diff --git a/tests/Unit/Middleware/HistoryMiddlewareTest.php b/tests/Unit/Middleware/HistoryMiddlewareTest.php
index 0feab1c8..4f25fc83 100644
--- a/tests/Unit/Middleware/HistoryMiddlewareTest.php
+++ b/tests/Unit/Middleware/HistoryMiddlewareTest.php
@@ -16,7 +16,7 @@ class HistoryMiddlewareTest extends TestCase
     /** @var HistoryMiddleware */
     private $middleware;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->journal = $this->getMockBuilder('Buzz\Middleware\History\Journal')
             ->disableOriginalConstructor()
diff --git a/tests/Unit/Middleware/LoggerMiddlewareTest.php b/tests/Unit/Middleware/LoggerMiddlewareTest.php
index ec503b30..1fe253ec 100644
--- a/tests/Unit/Middleware/LoggerMiddlewareTest.php
+++ b/tests/Unit/Middleware/LoggerMiddlewareTest.php
@@ -19,7 +19,14 @@ public function testLogger()
 
         // TODO Use PSR3 logger
         $logger = new CallbackLogger(function ($level, $message, array $context) use ($that) {
-            $that->assertRegExp('~^Sent "GET http://google.com/" in \d+ms$~', $message);
+            $pattern = '~^Sent "GET http://google.com/" in \d+ms$~';
+            if (method_exists($this, 'assertMatchesRegularExpression')) {
+                $that->assertMatchesRegularExpression($pattern, $message);
+
+                return;
+            }
+            // phpunit 7 compatibility
+            $that->assertRegExp($pattern, $message);
         });
 
         $request = new Request('GET', 'http://google.com/');
diff --git a/tests/Unit/Middleware/WsseAuthMiddlewareTest.php b/tests/Unit/Middleware/WsseAuthMiddlewareTest.php
index d7a80531..ffccf4c3 100644
--- a/tests/Unit/Middleware/WsseAuthMiddlewareTest.php
+++ b/tests/Unit/Middleware/WsseAuthMiddlewareTest.php
@@ -22,6 +22,13 @@ public function testBasicAuthHeader()
 
         $this->assertEquals('WSSE profile="UsernameToken"', $newRequest->getHeaderLine('Authorization'));
         $wsse = $newRequest->getHeaderLine('X-WSSE');
-        $this->assertRegExp('|UsernameToken Username="foo", PasswordDigest=".+?", Nonce=".+?", Created=".+?"|', $wsse);
+        $pattern = '|UsernameToken Username="foo", PasswordDigest=".+?", Nonce=".+?", Created=".+?"|';
+        if (method_exists($this, 'assertMatchesRegularExpression')) {
+            $this->assertMatchesRegularExpression($pattern, $wsse);
+
+            return;
+        }
+        // phpunit 7 compatibility
+        $this->assertRegExp($pattern, $wsse);
     }
 }