diff --git a/core/includes/common.inc b/core/includes/common.inc
index 3841d90..a18882b 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -375,7 +375,12 @@ function drupal_add_feed($url = NULL, $title = '') {
   $stored_feed_links = &drupal_static(__FUNCTION__, array());
 
   if (isset($url)) {
-    $stored_feed_links[$url] = theme('feed_icon', array('url' => $url, 'title' => $title));
+    $feed_icon = array(
+      '#theme' => 'feed_icon',
+      '#url' => $url,
+      '#title' => $title,
+    );
+    $stored_feed_links[$url] = drupal_render($feed_icon);
 
     $build['#attached']['drupal_add_html_head_link'][][] = array(
       'rel' => 'alternate',