diff --git mailchimp/modules/mailchimp_lists/mailchimp_lists.module mailchimp/modules/mailchimp_lists/mailchimp_lists.module
index 06f6049..c1b5e44 100644
--- mailchimp/modules/mailchimp_lists/mailchimp_lists.module
+++ mailchimp/modules/mailchimp_lists/mailchimp_lists.module
@@ -489,12 +489,14 @@ function mailchimp_lists_auth_newsletter_form(&$form, $list, $account) {
     }
     $mc_list = mailchimp_get_list($list->mc_list_id);

-    foreach ($mc_list['mergevars'] as $mergevar) {
-      // set the default value for merge fields if we have it
-      if ($mergevalues && isset($mergevalues[$mergevar['tag']]) && $mergevalues[$mergevar['tag']]) {
-        $mergevar['default'] = $mergevalues[$mergevar['tag']];
+    if (!empty($mc_list['mergevars'])) {
+      foreach ($mc_list['mergevars'] as $mergevar) {
+        // set the default value for merge fields if we have it
+        if ($mergevalues && isset($mergevalues[$mergevar['tag']]) && $mergevalues[$mergevar['tag']]) {
+          $mergevar['default'] = $mergevalues[$mergevar['tag']];
+        }
+        $form[$wrapper_key]['mergevars'][$mergevar['tag']] = mailchimp_lists_insert_drupal_form_tag($mergevar);
       }
-      $form[$wrapper_key]['mergevars'][$mergevar['tag']] = mailchimp_lists_insert_drupal_form_tag($mergevar);
     }
   }