diff --git a/plugins/OAuth2/Entity/Client.php b/plugins/OAuth2/Entity/Client.php
index 27ef342a6e..be3c188f20 100644
--- a/plugins/OAuth2/Entity/Client.php
+++ b/plugins/OAuth2/Entity/Client.php
@@ -187,7 +187,7 @@ class Client extends Entity implements ClientEntityInterface
     // @codeCoverageIgnoreEnd
     // }}} Autocode
 
-    public function getIdentifier()
+    public function getIdentifier(): string
     {
         return $this->getId();
     }
diff --git a/plugins/OAuth2/Repository/Client.php b/plugins/OAuth2/Repository/Client.php
index d0e396c1c3..dda5fa55c4 100644
--- a/plugins/OAuth2/Repository/Client.php
+++ b/plugins/OAuth2/Repository/Client.php
@@ -35,6 +35,7 @@ namespace Plugin\OAuth2\Repository;
 
 use App\Core\DB\DB;
 use App\Util\Exception\NotFoundException;
+use League\OAuth2\Server\Entities\ClientEntityInterface;
 use League\OAuth2\Server\Repositories\ClientRepositoryInterface;
 use Plugin\OAuth2\Entity;
 
@@ -63,7 +64,7 @@ class Client implements ClientRepositoryInterface
      * @throws \App\Util\Exception\DuplicateFoundException
      * @throws NotFoundException
      */
-    public function getClientEntity($clientIdentifier)
+    public function getClientEntity($clientIdentifier): ?ClientEntityInterface
     {
         return DB::findOneBy(Entity\Client::class, ['id' => $clientIdentifier]);
     }
diff --git a/src/Core/Form/FormTypeNonceExtension.php b/src/Core/Form/FormTypeNonceExtension.php
index 0d5e5ca804..f4461068df 100644
--- a/src/Core/Form/FormTypeNonceExtension.php
+++ b/src/Core/Form/FormTypeNonceExtension.php
@@ -36,7 +36,7 @@ class FormTypeNonceExtension extends AbstractTypeExtension implements EventSubsc
         $builder->addEventSubscriber($this);
     }
 
-    public static function getSubscribedEvents()
+    public static function getSubscribedEvents(): array
     {
         return [FormEvents::PRE_SUBMIT => 'preSubmit'];
     }
diff --git a/src/Core/I18n/TransExtractor.php b/src/Core/I18n/TransExtractor.php
index 04ee67aa19..71db8ba237 100644
--- a/src/Core/I18n/TransExtractor.php
+++ b/src/Core/I18n/TransExtractor.php
@@ -187,7 +187,7 @@ class TransExtractor extends AbstractFileExtractor implements ExtractorInterface
     /**
      * {@inheritDoc}
      */
-    protected function extractFromDirectory($directory)
+    protected function extractFromDirectory($directory): iterable
     {
         $finder = new Finder();
         return $finder->files()->name('*.php')->in($directory);
diff --git a/src/DependencyInjection/Compiler/SchemaDefDriver.php b/src/DependencyInjection/Compiler/SchemaDefDriver.php
index 351db20acf..ad4d41f9b3 100644
--- a/src/DependencyInjection/Compiler/SchemaDefDriver.php
+++ b/src/DependencyInjection/Compiler/SchemaDefDriver.php
@@ -96,7 +96,7 @@ class SchemaDefDriver extends StaticPHPDriver implements CompilerPassInterface
      * @param class-string      $class_name
      * @param ClassMetadataInfo $metadata   ClassMetadataInfo is the real type, but we need to override the method
      */
-    public function loadMetadataForClass($class_name, ClassMetadata $metadata)
+    public function loadMetadataForClass($class_name, ClassMetadata $metadata): void
     {
         $schema = $class_name::schemaDef();
 
diff --git a/src/Entity/LocalUser.php b/src/Entity/LocalUser.php
index 7db1a1fcf6..7cd27dfd66 100644
--- a/src/Entity/LocalUser.php
+++ b/src/Entity/LocalUser.php
@@ -408,7 +408,7 @@ class LocalUser extends Entity implements UserInterface, PasswordAuthenticatedUs
     /**
      * Returns the roles granted to the user
      */
-    public function getRoles()
+    public function getRoles(): array
     {
         return ActorLocalRoles::toArray($this->getActor()->getRoles());
     }
diff --git a/src/Security/Authenticator.php b/src/Security/Authenticator.php
index a6de495cd5..faff3cc8ab 100644
--- a/src/Security/Authenticator.php
+++ b/src/Security/Authenticator.php
@@ -194,7 +194,7 @@ class Authenticator extends AbstractFormLoginAuthenticator implements Authentica
         );
     }
 
-    protected function getLoginUrl()
+    protected function getLoginUrl(): string
     {
         return Router::url(self::LOGIN_ROUTE);
     }
diff --git a/src/Twig/Extension.php b/src/Twig/Extension.php
index 71493d98dd..e184eae9eb 100644
--- a/src/Twig/Extension.php
+++ b/src/Twig/Extension.php
@@ -38,14 +38,14 @@ use Twig\TwigTest;
 
 class Extension extends AbstractExtension
 {
-    public function getFilters()
+    public function getFilters(): array
     {
         return [
             // new TwigFilter('foo', [GSRuntime::class, 'foo']),
         ];
     }
 
-    public function getTests()
+    public function getTests(): array
     {
         return [
             new TwigTest('instanceof', [Runtime::class, 'isInstanceOf']),
diff --git a/src/Twig/Runtime.php b/src/Twig/Runtime.php
index bb1007141e..cff8b79365 100644
--- a/src/Twig/Runtime.php
+++ b/src/Twig/Runtime.php
@@ -219,16 +219,17 @@ class Runtime implements RuntimeExtensionInterface, EventSubscriberInterface
     /**
      * @codeCoverageIgnore
      */
-    public function onKernelRequest(RequestEvent $event)
+    public function onKernelRequest(RequestEvent $event): RequestEvent
     {
         // Request is not a service, can't find a better way to get it
         $this->request = $event->getRequest();
+        return $event;
     }
 
     /**
      * @codeCoverageIgnore
      */
-    public static function getSubscribedEvents()
+    public static function getSubscribedEvents(): array
     {
         return [KernelEvents::REQUEST => 'onKernelRequest'];
     }