diff --git a/src/wp-includes/class-wp.php b/src/wp-includes/class-wp.php
index 5298ff21ab..47ed0a04b4 100644
--- a/src/wp-includes/class-wp.php
+++ b/src/wp-includes/class-wp.php
@@ -308,7 +308,7 @@ class WP {
 					$this->query_vars[ $wpvar ] = (string) $this->query_vars[ $wpvar ];
 				} else {
 					foreach ( $this->query_vars[ $wpvar ] as $vkey => $v ) {
-						if ( ! is_object( $v ) ) {
+						if ( is_scalar( $v ) ) {
 							$this->query_vars[ $wpvar ][ $vkey ] = (string) $v;
 						}
 					}