diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 8d527df..dd2381f 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -2645,9 +2645,6 @@ function template_preprocess(&$variables, $hook) {
     'title_attributes' => clone $default_attributes,
     'content_attributes' => clone $default_attributes,
   );
-
-  // Initialize html class attribute for the current hook.
-  $variables['attributes']['class'][] = drupal_html_class($hook);
 }
 
 /**