diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 52ce316..1d27907 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -2399,9 +2399,11 @@ function template_preprocess_region(&$variables) {
   // Create the $content variable that templates expect.
   $variables['content'] = $variables['elements']['#children'];
   $variables['region'] = $variables['elements']['#region'];
-
   $variables['attributes']['class'][] = 'region';
   $variables['attributes']['class'][] = drupal_html_class('region-' . $variables['region']);
+  if (!empty($variables['elements']['#attributes']['class'])) {
+    $variables['attributes']['class'] = array_merge($variables['elements']['#attributes']['class'], $variables['attributes']['class']);
+  }
 }
 
 /**