diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
index 2f5b3d4d..b141ada2 100644
--- a/.github/workflows/run-tests.yml
+++ b/.github/workflows/run-tests.yml
@@ -19,7 +19,7 @@ jobs:
         continue-on-error: ${{ matrix.allowed-to-fail }}
 
         strategy:
-            matrix:                
+            matrix:
                 php-version: ['7.2.5', '7.3', '7.4', '8.0']
                 variant: [normal]
                 dependencies: [highest]
@@ -46,6 +46,11 @@ jobs:
                     variant: 'symfony/symfony:"5.1"'
                     allowed-to-fail: false
                     symfony-version: 5.1
+                  - php-version: '8.0'
+                    dependencies: highest
+                    variant: 'symfony/symfony:"6.0.*"'
+                    allowed-to-fail: false
+                    symfony-version: 6.0
         steps:
             - name: "Checkout code"
               uses: actions/checkout@v2.3.3
@@ -65,12 +70,12 @@ jobs:
             - name: Install variant
               if: matrix.variant != 'normal'
               run: composer require ${{ matrix.variant }} --no-update
-              
+
             - name: "Install Composer dependencies (${{ matrix.dependencies }})"
               uses: "ramsey/composer-install@v1"
               with:
                 dependency-versions: "${{ matrix.dependencies }}"
-                composer-options: "--prefer-dist"              
+                composer-options: "--prefer-dist"
 
             - name: "Install PHPUnit"
               run: vendor/bin/simple-phpunit install
@@ -80,9 +85,9 @@ jobs:
 
             - name: "Run unit tests"
               run: vendor/bin/phpunit --coverage-text --verbose
-              
-            - name: "Run phantomjs tests"  
+
+            - name: "Run phantomjs tests"
               run: phantomjs Resources/js/run-qunit.js file://`pwd`/Resources/js/index.html
-            
+
             - name: "Run phantomjs tests ES5"
               run: phantomjs Resources/js/run-qunit.js file://`pwd`/Resources/js/index-with-es5-shim.html
diff --git a/.gitignore b/.gitignore
index e96cdacf..944eac06 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 node_modules
 vendor/
 composer.lock
+.phpunit.result.cache
diff --git a/Command/DumpCommand.php b/Command/DumpCommand.php
index efcedd2e..bd3f2ae0 100644
--- a/Command/DumpCommand.php
+++ b/Command/DumpCommand.php
@@ -90,7 +90,7 @@ protected function initialize(InputInterface $input, OutputInterface $output)
     }
 
     /**
-     * {@inheritDoc}
+     * @return int
      */
     protected function execute(InputInterface $input, OutputInterface $output)
     {
diff --git a/Tests/Fixtures/app/AppKernel.php b/Tests/Fixtures/app/AppKernel.php
index a9661f78..2ff1e5fb 100644
--- a/Tests/Fixtures/app/AppKernel.php
+++ b/Tests/Fixtures/app/AppKernel.php
@@ -34,7 +34,7 @@ public function __construct($environment, $debug)
         parent::__construct($environment, $debug);
     }
 
-    public function registerBundles()
+    public function registerBundles(): iterable
     {
         return array(
             new \Symfony\Bundle\FrameworkBundle\FrameworkBundle(),
@@ -44,22 +44,22 @@ public function registerBundles()
         );
     }
 
-    public function getRootDir()
+    public function getRootDir(): string
     {
         return __DIR__;
     }
 
-    public function getProjectDir()
+    public function getProjectDir(): string
     {
         return __DIR__.'/../';
     }
 
-    public function getCacheDir()
+    public function getCacheDir(): string
     {
         return sys_get_temp_dir().'/'.Kernel::VERSION.'/bazinga-js-translation/cache/'.$this->environment;
     }
 
-    public function getLogDir()
+    public function getLogDir(): string
     {
         return sys_get_temp_dir().'/'.Kernel::VERSION.'/bazinga-js-translation/logs';
     }
diff --git a/Tests/WebTestCase.php b/Tests/WebTestCase.php
index d3031064..7b1248c0 100644
--- a/Tests/WebTestCase.php
+++ b/Tests/WebTestCase.php
@@ -6,6 +6,7 @@
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\Filesystem\Filesystem;
 use Symfony\Component\HttpKernel\Kernel;
+use Symfony\Component\HttpKernel\KernelInterface;
 use Bazinga\Bundle\JsTranslationBundle\Tests\Fixtures\app\AppKernel;
 
 abstract class WebTestCase extends BaseWebTestCase
@@ -30,12 +31,12 @@ protected static function getContainer(): ContainerInterface
         return static::$kernel->getContainer();
     }
 
-    protected static function getKernelClass()
+    protected static function getKernelClass(): string
     {
         return AppKernel::class;
     }
 
-    protected static function createKernel(array $options = array())
+    protected static function createKernel(array $options = array()): KernelInterface
     {
         $class = self::getKernelClass();
 
diff --git a/composer.json b/composer.json
index 394f10c7..dbde169d 100644
--- a/composer.json
+++ b/composer.json
@@ -12,20 +12,20 @@
     ],
     "require": {
         "php": ">=7.2.5",
-        "symfony/framework-bundle": "~4.4|~5.0",
-        "symfony/finder": "~4.4|~5.0",
-        "symfony/console": "~4.4|~5.0",
-        "symfony/intl": "~4.4|~5.0",
-        "symfony/translation":  "~4.4|~5.0",
-        "symfony/twig-bundle": "~4.4|~5.0"
+        "symfony/framework-bundle": "~4.4|~5.0|~6.0",
+        "symfony/finder": "~4.4|~5.0|~6.0",
+        "symfony/console": "~4.4|~5.0|~6.0",
+        "symfony/intl": "~4.4|~5.0|~6.0",
+        "symfony/translation":  "~4.4|~5.0|~6.0",
+        "symfony/twig-bundle": "~4.4|~5.0|~6.0"
     },
     "require-dev": {
-        "symfony/asset": "~4.4|~5.0",
-        "symfony/filesystem": "~4.4|~5.0",
-        "symfony/yaml": "~4.4|~5.0",
-        "symfony/browser-kit": "~4.4|~5.0",
-        "symfony/twig-bundle": "~4.4|~5.0",
-        "symfony/phpunit-bridge": "^5.0",
+        "symfony/asset": "~4.4|~5.0|~6.0",
+        "symfony/filesystem": "~4.4|~5.0|~6.0",
+        "symfony/yaml": "~4.4|~5.0|~6.0",
+        "symfony/browser-kit": "~4.4|~5.0|~6.0",
+        "symfony/twig-bundle": "~4.4|~5.0|~6.0",
+        "symfony/phpunit-bridge": "^5.0|^6.0",
         "phpunit/phpunit": "^4.8|~5.7|~6.5|~8"
     },
     "replace": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 225fccf7..3ba62515 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -23,4 +23,10 @@
             </exclude>
         </whitelist>
     </filter>
+    <listeners>
+        <listener class="Symfony\Bridge\PhpUnit\SymfonyTestsListener"/>
+    </listeners>
+    <php>
+        <env name="SYMFONY_DEPRECATIONS_HELPER" value="max[direct]=0"/>
+    </php>
 </phpunit>