diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index 1fd497de2c5..796ebcdaeed 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -810,7 +810,7 @@ function drupal_settings_initialize() {
  *   than by consulting the database.
  *
  * @return
- *   The filename of the requested item.
+ *   The filename of the requested item or NULL if the item is not found.
  */
 function drupal_get_filename($type, $name, $filename = NULL) {
   // The location of files will not change during the request, so do not use