diff -u b/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
--- b/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -208,11 +208,6 @@
  *   The filename of the requested item or NULL if the item is not found.
  */
 function drupal_get_filename($type, $name, $filename = NULL) {
-  // Return NULL right away if $type or $name is empty.
-  if (empty($type) || empty($name)) {
-    return NULL;
-  }
-
   // The location of files will not change during the request, so do not use
   // drupal_static().
   static $files = array();