diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 5c38525..1e45b2a 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -2364,8 +2364,7 @@ function template_preprocess_html(&$variables) {
   $variables['body_attributes_array'] = array();
 
   // HTML element attributes.
-  $variables['html_attributes_array']['xmlns'] = "http://www.w3.org/1999/xhtml";
-  $variables['html_attributes_array']['xml:lang'] = $GLOBALS['language']->language;
+  $variables['html_attributes_array']['lang'] = $GLOBALS['language']->language;
   $variables['html_attributes_array']['dir'] = $GLOBALS['language']->direction ? 'rtl' : 'ltr';
 
   // Add favicon.
diff --git a/core/modules/rdf/rdf.module b/core/modules/rdf/rdf.module
index 1a29646..eae0f9e 100644
--- a/core/modules/rdf/rdf.module
+++ b/core/modules/rdf/rdf.module
@@ -624,7 +624,7 @@ function rdf_preprocess_user_profile(&$variables) {
  * Implements MODULE_preprocess_HOOK().
  */
 function rdf_preprocess_username(&$variables) {
-  // Because xml:lang is set on the HTML element that wraps the page, the
+  // Because lang is set on the HTML element that wraps the page, the
   // username inherits this language attribute. However, since the username
   // might not be transliterated to the same language that the content is in,
   // we do not want it to inherit the language attribute, so we set the