diff --git a/sites/all/modules/contrib/dart/dart.module b/sites/all/modules/contrib/dart/dart.module
index 972b94e..5b421c8 100644
--- a/sites/all/modules/contrib/dart/dart.module
+++ b/sites/all/modules/contrib/dart/dart.module
@@ -564,7 +564,7 @@ function _dart_get_page_key_vals() {
 function template_preprocess_dart_tag(&$variables) {
   $tag = $variables['tag'];
 
-  $variables['attributes_array']['class'] = 'dart-tag dart-name-' . $tag->machinename;
+  $variables['classes_array'][] = 'dart-tag dart-name-' . $tag->machinename;
   $variables['json_tag'] = drupal_json_encode($tag);
   $variables['load_last']   = variable_get('dart_load_last', '0');