--- webform/webform.module.dist	2012-02-04 11:38:13.000000001 -0500
+++ webform/webform.module	2012-02-04 11:36:32.000000001 -0500
@@ -1826,7 +1826,7 @@
     );
     $form['details']['sid'] = array(
       '#type' => 'hidden',
-      '#value' => isset($submission->sid) ? $submission->sid : '',
+      '#value' => isset($submission->sid) ? $submission->sid : '0',
     );
     $form['details']['uid'] = array(
       '#type' => 'value',