diff --git a/wp-includes/nav-menu-template.php b/wp-includes/nav-menu-template.php
index 5feac80..111b705 100644
--- a/wp-includes/nav-menu-template.php
+++ b/wp-includes/nav-menu-template.php
@@ -549,6 +549,10 @@ function _wp_menu_item_classes_by_context( &$menu_items ) {
 			$current_url = set_url_scheme( 'http://' . $_SERVER['HTTP_HOST'] . $_root_relative_current );
 			$raw_item_url = strpos( $menu_item->url, '#' ) ? substr( $menu_item->url, 0, strpos( $menu_item->url, '#' ) ) : $menu_item->url;
 			$item_url = untrailingslashit( $raw_item_url );
+			preg_match( '/^(http:\/\/|https:\/\/)/', $item_url, $is_item_url_absolute );
+			if( $is_item_url_absolute ) {
+				$item_url = set_url_scheme( $item_url );
+			}
 			$_indexless_current = untrailingslashit( preg_replace( '/' . preg_quote( $wp_rewrite->index, '/' ) . '$/', '', $current_url ) );
 
 			if ( $raw_item_url && in_array( $item_url, array( $current_url, $_indexless_current, $_root_relative_current ) ) ) {