Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.277
diff -u -p -r1.277 form.inc
--- includes/form.inc	18 Jul 2008 07:06:24 -0000	1.277
+++ includes/form.inc	31 Jul 2008 10:36:28 -0000
@@ -2207,7 +2207,7 @@ function _form_set_class(&$element, $cla
   if ($element['#required']) {
     $class[] = 'required';
   }
-  if (form_get_error($element)) {
+  if (form_get_error($element) !== NULL) {
     $class[] = 'error';
   }
   if (isset($element['#attributes']['class'])) {