diff --git a/handlers/views_handler_argument.inc b/handlers/views_handler_argument.inc
index d0bbac6..194124a 100644
--- a/handlers/views_handler_argument.inc
+++ b/handlers/views_handler_argument.inc
@@ -418,7 +418,7 @@ class views_handler_argument extends views_handler {
     // Let the plugins do validation.
     $default_id = $form_state['values']['options']['default_argument_type'];
     $plugin = $this->get_plugin('argument default', $default_id);
-    if ($plugin) {
+    if ($plugin && isset($form_state['values']['options']['argument_default'][$default_id])) {
       $plugin->options_validate($form['argument_default'][$default_id], $form_state, $form_state['values']['options']['argument_default'][$default_id]);
     }