diff --git a/metatag_google_plus/metatag_google_plus.module b/metatag_google_plus/metatag_google_plus.module
index 213467a..c311922 100644
--- a/metatag_google_plus/metatag_google_plus.module
+++ b/metatag_google_plus/metatag_google_plus.module
@@ -55,10 +55,17 @@ function theme_metatag_google_plus($variables) {
  * themes as Zen will serialize RDF Namespaces into an RDFa 1.1 prefix
  * attribute, which means itemtype will be included in prefix="...".
  *
+ * You need to add the $schemaorg variable in the html tag of your template after $rdf_namespaces
+ *
  * @see zen_preprocess_html()
  */
 function metatag_google_plus_preprocess_html(&$variables) {
+
+  if (!isset($variables['schemaorg'])) {
+    $variables['schemaorg'] = '';
+  }
+
   if (isset($variables['itemtype']) && !function_exists('zen_preprocess_html')) {
-    $variables['rdf_namespaces'] .= "\n  itemscope itemtype=\"http://schema.org/{$variables['itemtype']}\"";
+    $variables['schemaorg'] .= "itemscope itemtype=\"http://schema.org/{$variables['itemtype']}\"";
   }
 }