diff --git a/wp-includes/kses.php b/wp-includes/kses.php
index ae37fc26c5..79f5366fe5 100644
--- a/wp-includes/kses.php
+++ b/wp-includes/kses.php
@@ -182,8 +182,10 @@ if (!CUSTOM_TAGS) {
 			'class' => array (),
 			'dir' => array (),
 			'align' => array (),
+			'lang' => array (),
 			'style' => array (),
-			'title' => array ()),
+			'title' => array (),
+			'xml:lang' => array()),
 		'strike' => array(),
 		'strong' => array(),
 		'sub' => array(),