diff --git a/src/bundle/DependencyInjection/IbexaSystemInfoExtension.php b/src/bundle/DependencyInjection/IbexaSystemInfoExtension.php
index 11193a0..85aaa77 100644
--- a/src/bundle/DependencyInjection/IbexaSystemInfoExtension.php
+++ b/src/bundle/DependencyInjection/IbexaSystemInfoExtension.php
@@ -12,6 +12,7 @@
 use Ibexa\Bundle\SystemInfo\SystemInfo\Collector\IbexaSystemInfoCollector;
 use Ibexa\Bundle\SystemInfo\SystemInfo\Value\IbexaSystemInfo;
 use Ibexa\Contracts\Core\Ibexa;
+use Symfony\Component\Config\Definition\ConfigurationInterface;
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Extension\PrependExtensionInterface;
@@ -24,12 +25,12 @@ class IbexaSystemInfoExtension extends Extension implements PrependExtensionInte
     public const METRICS_TAG = 'ibexa.system_info.metrics';
     public const SERVICE_TAG = 'ibexa.system_info.service';
 
-    public function getAlias()
+    public function getAlias(): string
     {
         return self::EXTENSION_NAME;
     }
 
-    public function getConfiguration(array $config, ContainerBuilder $container)
+    public function getConfiguration(array $config, ContainerBuilder $container): ?ConfigurationInterface
     {
         return new Configuration();
     }
diff --git a/src/bundle/EventSubscriber/AddXPoweredByHeader.php b/src/bundle/EventSubscriber/AddXPoweredByHeader.php
index f878262..a6fc162 100644
--- a/src/bundle/EventSubscriber/AddXPoweredByHeader.php
+++ b/src/bundle/EventSubscriber/AddXPoweredByHeader.php
@@ -27,7 +27,7 @@ public function __construct(string $installationName)
         $this->installationName = $installationName;
     }
 
-    public static function getSubscribedEvents()
+    public static function getSubscribedEvents(): array
     {
         return [KernelEvents::RESPONSE => 'promotePlatform'];
     }