Index: webform.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/webform/webform.module,v
retrieving revision 1.136
diff -u -p -r1.136 webform.module
--- webform.module	20 Jun 2009 23:04:58 -0000	1.136
+++ webform.module	13 Oct 2009 20:03:26 -0000
@@ -1235,6 +1235,8 @@ function webform_client_form($form_state
             '#type' => 'submit',
             '#value' => $prev_page,
             '#weight' => 1000,
+            // skip_validation.module key
+            '#skip_required_validation' => TRUE,
           );
         }
         if ($page_num == $page_count) {