diff --git a/core/includes/common.inc b/core/includes/common.inc
index 5e8e2d1..8ddb820 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -1961,9 +1961,9 @@ function l($text, $path, array $options = array()) {
   // The query parameters of an active link are equal to the current parameters.
   && ($variables['options']['query'] == $active['query']);
 
-  // Add the "active" class if appropriate.
+  // Add the "is-active" class if appropriate.
   if ($variables['url_is_active']) {
-    $variables['options']['attributes']['class'][] = 'active';
+    $variables['options']['attributes']['class'][] = 'is-active';
   }
 
   // Remove all HTML and PHP tags from a tooltip, calling expensive strip_tags()