diff --git a/url_replace_filter.module b/url_replace_filter.module
index 8097eaa..8e0ab93 100755
--- a/url_replace_filter.module
+++ b/url_replace_filter.module
@@ -46,13 +46,13 @@ function _url_replace_filter_process($text, $format) {
  * Settings for the HTML filter.
  */
 function _url_replace_filter_settings($format) {
-  $form['#tree'] = TRUE;
   $form['url_replace_filter_'. $format] = array(
     '#type' => 'fieldset',
     '#title' => t('URL Replace Filter'),
     '#collapsible' => TRUE,
     '#collapsed' => FALSE,
     '#theme' => 'url_replace_filter_settings_form',
+    '#tree' => TRUE,
   );
   $settings = _url_replace_filter_get_settings($format);
   foreach ($settings as $index => $setting) {