diff --git a/pkg/async-event-dispatcher/DependencyInjection/Configuration.php b/pkg/async-event-dispatcher/DependencyInjection/Configuration.php
index 56151e956..785d17197 100644
--- a/pkg/async-event-dispatcher/DependencyInjection/Configuration.php
+++ b/pkg/async-event-dispatcher/DependencyInjection/Configuration.php
@@ -10,7 +10,7 @@ class Configuration implements ConfigurationInterface
     /**
      * {@inheritdoc}
      */
-    public function getConfigTreeBuilder()
+    public function getConfigTreeBuilder(): TreeBuilder
     {
         if (method_exists(TreeBuilder::class, 'getRootNode')) {
             $tb = new TreeBuilder('enqueue_async_event_dispatcher');