--- nodereference_url.module	2010-04-07 09:10:25.000000000 +0200
+++ /home/reynier/drupal/sites/oms/sites/all/modules/nodereference_url/nodereference_url.module	2010-08-16 14:51:03.840899800 +0200
@@ -448,7 +448,9 @@ function nodereference_url_process_selec
   if (isset($element['nid']['nid']['#options'])) {
     $field = content_fields($element['#field_name'], $element['#type_name']);
     $field['widget']['type'] = 'optionwidgets_select';
-    $element['nid']['nid']['#options'] = array('' => theme('optionwidgets_none', $field)) + $element['nid']['nid']['#options'];
+    if (!$element['nid']['#required']) {
+        $element['nid']['nid']['#options'] = array('' => theme('optionwidgets_none', $field)) + $element['nid']['nid']['#options'];
+    }
   }
 
   return $element;