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..c53ba34 100644
--- a/core/modules/rdf/rdf.module
+++ b/core/modules/rdf/rdf.module
@@ -624,13 +624,13 @@ 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
   // attribute to an empty string.
-  if (empty($variables['attributes_array']['xml:lang'])) {
-    $variables['attributes_array']['xml:lang'] = '';
+  if (empty($variables['attributes_array']['lang'])) {
+    $variables['attributes_array']['lang'] = '';
   }
 
   // $variables['account'] is a pseudo account object, and as such, does not
diff --git a/core/modules/rdf/rdf.test b/core/modules/rdf/rdf.test
index 50177ca..c05127e 100644
--- a/core/modules/rdf/rdf.test
+++ b/core/modules/rdf/rdf.test
@@ -384,10 +384,10 @@ class RdfMappingDefinitionTestCase extends TaxonomyWebTestCase {
     $this->drupalGet('node/' . $node->nid);
     // Ensures the default bundle mapping for user is used on the Authored By
     // information on the node.
-    $author_about = $this->xpath('//a[@typeof="sioc:UserAccount" and @about=:account-uri and @property="foaf:name" and contains(@xml:lang, "")]', array(
+    $author_about = $this->xpath('//a[@typeof="sioc:UserAccount" and @about=:account-uri and @property="foaf:name" and contains(@lang, "")]', array(
       ':account-uri' => $account_uri,
     ));
-    $this->assertTrue(!empty($author_about), t('RDFa markup found on author information on post. xml:lang on username is set to empty string.'));
+    $this->assertTrue(!empty($author_about), t('RDFa markup found on author information on post. The lang attribute on username is set to empty string.'));
   }
 
   /**
diff --git a/core/modules/search/search.pages.inc b/core/modules/search/search.pages.inc
index 833ea8b..24ea707 100644
--- a/core/modules/search/search.pages.inc
+++ b/core/modules/search/search.pages.inc
@@ -110,8 +110,8 @@ function template_preprocess_search_result(&$variables) {
   $variables['url'] = check_url($result['link']);
   $variables['title'] = check_plain($result['title']);
   if (isset($result['language']) && $result['language'] != $language->language && $result['language'] != LANGUAGE_NONE) {
-    $variables['title_attributes_array']['xml:lang'] = $result['language'];
-    $variables['content_attributes_array']['xml:lang'] = $result['language'];
+    $variables['title_attributes_array']['lang'] = $result['language'];
+    $variables['content_attributes_array']['lang'] = $result['language'];
   }
 
   $info = array();