diff --git a/wp-includes/query.php b/wp-includes/query.php
index ff7155fde3..7d95230405 100644
--- a/wp-includes/query.php
+++ b/wp-includes/query.php
@@ -1398,6 +1398,7 @@ class WP_Query {
 			, 's'
 			, 'sentence'
 			, 'fields'
+			, 'menu_order'
 		);
 
 		foreach ( $keys as $key ) {