diff --git a/Creational/Pool/StringReverseWorker.php b/Creational/Pool/StringReverseWorker.php
index 378f221..ca7a5f9 100644
--- a/Creational/Pool/StringReverseWorker.php
+++ b/Creational/Pool/StringReverseWorker.php
@@ -10,7 +10,7 @@ class StringReverseWorker
     {
     }
 
-    public function run(string $text)
+    public function run(string $text): string
     {
         return strrev($text);
     }