diff --git a/src/Php73/bootstrap.php b/src/Php73/bootstrap.php
index 6d555807e..049b8bb8a 100644
--- a/src/Php73/bootstrap.php
+++ b/src/Php73/bootstrap.php
@@ -26,6 +26,6 @@ function array_key_first(array $array) { foreach ($array as $key => $value) { re
     }
 
     if (!function_exists('array_key_last')) {
-        function array_key_last(array $array) { $key = null; foreach ($array as $key => $value); return $key; }
+        function array_key_last(array $array) { end($array); return key($array); }
     }
 }