Index: includes/theme.inc
===================================================================
--- includes/theme.inc	(revision 36355)
+++ includes/theme.inc	(working copy)
@@ -587,6 +587,7 @@
 
   if (is_array($hook)) {
     foreach ($hook as $candidate) {
+      $candidate = strtolower($candidate);
       if (isset($hooks[$candidate])) {
         break;
       }