diff --git a/modules/filter/filter.admin.inc b/modules/filter/filter.admin.inc
index 36f3d67..71d53d9 100644
--- a/modules/filter/filter.admin.inc
+++ b/modules/filter/filter.admin.inc
@@ -160,8 +160,11 @@ function filter_admin_format_form(&$form_state, $format) {
  * Validate filter format form submissions.
  */
 function filter_admin_format_form_validate($form, &$form_state) {
+  $name = trim($form_state['values']['name']);
+  if( $name == 'default' ) {
+    form_set_error('name', t('Filter format name "default" is reserved.', array('%name' => $name)));
+  } 
   if (!isset($form_state['values']['format'])) {
-    $name = trim($form_state['values']['name']);
     $result = db_fetch_object(db_query("SELECT format FROM {filter_formats} WHERE name='%s'", $name));
     if ($result) {
       form_set_error('name', t('Filter format names need to be unique. A format named %name already exists.', array('%name' => $name)));