diff --git a/core/includes/form.inc b/core/includes/form.inc
index aa6d1c4..4b1720e 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -4755,7 +4755,7 @@ function theme_form_element($variables) {
  * @ingroup themeable
  */
 function theme_form_required_marker($variables) {
-  if ($variables['element']['#required']) {
+  if (!empty($variables['element']['#required'])) {
     $attributes = array(
       'class' => 'form-required',
       'title' => t('This field is required.'),