diff --git includes/iso.inc includes/iso.inc
index ed2bfdd..88c2a04 100644
--- includes/iso.inc
+++ includes/iso.inc
@@ -16,9 +16,9 @@
  *   An array of all country code => country name pairs.
  */
 function _country_get_predefined_list() {
-  static $countries;
+  $countries = &drupal_static(__FUNCTION__, array());
 
-  if (isset($countries)) {
+  if (!empty($countries)) {
     return $countries;
   }
   $t = get_t();