diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index 448e65f..054e7b5 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -220,7 +220,9 @@ function system_themes_page() {
   uasort($theme_groups['enabled'], 'system_sort_themes');
   drupal_alter('system_themes_page', $theme_groups);
 
-  $build = array();
+  $build = array(
+    '#sorted' => TRUE,
+  );
   $build['system_themes_page'] = array(
     '#theme' => 'system_themes_page',
     '#theme_groups' => $theme_groups,