diff --git a/library/Zend/Registry.php b/library/Zend/Registry.php
index 32d4e62bf8..ef1ce0a6c6 100644
--- a/library/Zend/Registry.php
+++ b/library/Zend/Registry.php
@@ -202,7 +202,7 @@ public function __construct($array = array(), $flags = parent::ARRAY_AS_PROPS)
      * Workaround for http://bugs.php.net/bug.php?id=40442 (ZF-960).
      */
     #[\ReturnTypeWillChange]
-    public function offsetExists($index)
+    public function offsetExists($index) : bool
     {
         return array_key_exists($index, $this);
     }