diff --git a/event_dispatcher.rst b/event_dispatcher.rst
index ffa9e67aa0d..13a3bbb0297 100644
--- a/event_dispatcher.rst
+++ b/event_dispatcher.rst
@@ -728,7 +728,7 @@ this::
             return $this->subject;
         }
 
-        public function setSubject(string $subject): string
+        public function setSubject(string $subject): void
         {
             $this->subject = $subject;
         }