diff --git a/src/Resources/skeleton/message/MessageHandler.tpl.php b/src/Resources/skeleton/message/MessageHandler.tpl.php
index 1164c960c..1c55c72aa 100644
--- a/src/Resources/skeleton/message/MessageHandler.tpl.php
+++ b/src/Resources/skeleton/message/MessageHandler.tpl.php
@@ -7,7 +7,7 @@
 #[AsMessageHandler]
 final class <?= $class_name ?>
 {
-    public function __invoke(<?= $message_class_name ?> $message)
+    public function __invoke(<?= $message_class_name ?> $message): void
     {
         // do something with your message
     }