diff --git a/src/Functional/HStringWalk.php b/src/Functional/HStringWalk.php
index <HASH>..<HASH> 100644
--- a/src/Functional/HStringWalk.php
+++ b/src/Functional/HStringWalk.php
@@ -9,7 +9,7 @@ class HStringWalk
      * @param HString &$hString
      * @param callable $func
      */
-    public static function walk(HString &$hString, callable $func)
+    public static function walk(HString $hString, callable $func)
     {
         $size = $hString->count();
Remove object alias since objects are always passed by reference