diff --git a/composer.json b/composer.json
index 84b435a..f9a766e 100644
--- a/composer.json
+++ b/composer.json
@@ -11,12 +11,12 @@
     ],
     "require": {
         "php": ">=7.2.0",
-        "symfony/http-foundation": "~2.1|~3.0|~4.0|~5.0",
-        "symfony/http-kernel": "~2.1|~3.0|~4.0|~5.0"
+        "symfony/http-foundation": "~2.1|~3.0|~4.0|~5.0|~6.0",
+        "symfony/http-kernel": "~2.1|~3.0|~4.0|~5.0|~6.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~8.0",
-        "symfony/routing": "^5.0"
+        "phpunit/phpunit": "~9.0",
+        "symfony/routing": "^6.0"
     },
     "scripts": {
         "test": "phpunit --coverage-text"
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 58f6414..b1ac8d6 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -11,9 +11,6 @@
         <testsuite name="unit">
             <directory>./tests/unit/</directory>
         </testsuite>
-        <testsuite name="integration">
-            <directory>./tests/integration/</directory>
-        </testsuite>
         <testsuite name="functional">
             <directory>./tests/functional/</directory>
         </testsuite>
diff --git a/src/Stack/StackedHttpKernel.php b/src/Stack/StackedHttpKernel.php
index f89a4db..2925dec 100644
--- a/src/Stack/StackedHttpKernel.php
+++ b/src/Stack/StackedHttpKernel.php
@@ -18,7 +18,7 @@ public function __construct(HttpKernelInterface $app, array $middlewares)
         $this->middlewares = $middlewares;
     }
 
-    public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true)
+    public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true): Response
     {
         return $this->app->handle($request, $type, $catch);
     }
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index b7ccedd..7b462e2 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -44,7 +44,7 @@ public function __construct()
         $this->kernel = new HttpKernel($this->dispatcher, $controllerResolver, new RequestStack(), $argumentResolver);
     }
 
-    public function handle(Request $request, int $type = HttpKernelInterface::MASTER_REQUEST, bool $catch = true)
+    public function handle(Request $request, int $type = HttpKernelInterface::MASTER_REQUEST, bool $catch = true): Response
     {
         return $this->kernel->handle($request);
     }
diff --git a/tests/functional/ApplicationTest.php b/tests/functional/ApplicationTest.php
index 82c6ae9..61181f9 100644
--- a/tests/functional/ApplicationTest.php
+++ b/tests/functional/ApplicationTest.php
@@ -6,6 +6,7 @@
 use PHPUnit\Framework\TestCase;
 use Stack\Builder;
 use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
 
 class ApplicationTest extends TestCase
@@ -45,7 +46,7 @@ public function __construct(HttpKernelInterface $app, $appendix)
         $this->appendix = $appendix;
     }
 
-    public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true)
+    public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true): Response
     {
         $response = clone $this->app->handle($request, $type, $catch);
         $response->setContent($response->getContent().$this->appendix);
diff --git a/tests/unit/Stack/BuilderTest.php b/tests/unit/Stack/BuilderTest.php
index a48487d..0a5e733 100644
--- a/tests/unit/Stack/BuilderTest.php
+++ b/tests/unit/Stack/BuilderTest.php
@@ -193,7 +193,7 @@ public function __construct(HttpKernelInterface $app, $appendix)
         $this->appendix = $appendix;
     }
 
-    public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true)
+    public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true): Response
     {
         $response = clone $this->app->handle($request, $type, $catch);
         $response->setContent($response->getContent().$this->appendix);
diff --git a/tests/unit/Stack/StackedHttpKernelTest.php b/tests/unit/Stack/StackedHttpKernelTest.php
index aadb053..ab0c901 100644
--- a/tests/unit/Stack/StackedHttpKernelTest.php
+++ b/tests/unit/Stack/StackedHttpKernelTest.php
@@ -119,7 +119,7 @@ public function __construct(HttpKernelInterface $kernel = null)
         $this->kernel = $kernel;
     }
 
-    public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true)
+    public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true): Response
     {
         $this->handleCallCount++;