Index: date_api.module
===================================================================
--- date_api.module	(revision 7409)
+++ date_api.module	(working copy)
@@ -707,13 +707,14 @@
  *   A translated date string in the requested format.
  */
 function date_format_date($date, $type = 'medium', $format = '', $langcode = NULL) {
-  if (get_class($date) != 'DateTime') {
-    $date = date_make_date($date);
-  }
   if (empty($date)) {
     return '';
   }
   
+  if (get_class($date) != 'DateTime') {
+    $date = date_make_date($date);
+  }
+
   switch ($type) {
     case 'small':
     case 'short':