diff --git a/src/Elasticsearch/Connections/Connection.php b/src/Elasticsearch/Connections/Connection.php
index 928cefe05..ea0cfd136 100644
--- a/src/Elasticsearch/Connections/Connection.php
+++ b/src/Elasticsearch/Connections/Connection.php
@@ -327,7 +327,7 @@ private function wrapHandler(callable $handler)
     private function getURI($uri, $params)
     {
         if (isset($params) === true && !empty($params)) {
-            array_walk($params, function (&$value, &$key) {
+            array_walk($params, function (&$value) {
                 if ($value === true) {
                     $value = 'true';
                 } elseif ($value === false) {