diff --git a/includes/webform.components.inc b/includes/webform.components.inc
index 5c160f5..02c5e0f 100644
--- a/includes/webform.components.inc
+++ b/includes/webform.components.inc
@@ -1067,15 +1067,16 @@ function webform_validate_unique($element, $form_state) {
   if ($element['#value'] !== '') {
     $nid = $form_state['values']['details']['nid'];
     $sid = $form_state['values']['details']['sid'];
-    $count = db_select('webform_submitted_data')
+    $query = db_select('webform_submitted_data')
       ->fields('webform_submitted_data', array('sid'))
       ->condition('nid', $nid)
       ->condition('cid', $element['#webform_component']['cid'])
-      ->condition('sid', $sid, '<>')
       ->condition('data', $element['#value'])
-      ->range(0, 1) // More efficient than using countQuery() for data checks.
-      ->execute()
-      ->fetchField();
+      ->range(0, 1); // More efficient than using countQuery() for data checks.
+    if ($sid) {
+      $query->condition('sid', $sid, '<>');
+    }
+    $count = $query->execute()->fetchField();
     if ($count) {
       form_error($element, t('The value %value has already been submitted once for the %title field. You may have already submitted this form, or you need to use a different value.', array('%value' => $element['#value'], '%title' => $element['#title'])));
     }