Index: wp-includes/nav-menu-template.php
===================================================================
--- wp-includes/nav-menu-template.php	(revision 23307)
+++ wp-includes/nav-menu-template.php	(working copy)
@@ -251,7 +251,7 @@
  * @param array $menu_items The current menu item objects to which to add the class property information.
  */
 function _wp_menu_item_classes_by_context( &$menu_items ) {
-	global $wp_query;
+	global $wp_query, $wp_rewrite;
 
 	$queried_object = $wp_query->get_queried_object();
 	$queried_object_id = (int) $wp_query->queried_object_id;