--- filebrowser.admin.inc
+++ filebrowser.admin.inc
@@ -28,9 +28,9 @@
       '#tree' => TRUE
     )
   );
-  $form['filebrowser'] = array_merge($form['filebrowser'], (array)_filebrowser_form_presentation_part());
-  $form['filebrowser'] = array_merge($form['filebrowser'], (array)_filebrowser_form_rights_part());
-  $form['filebrowser'] = array_merge($form['filebrowser'], (array)_filebrowser_form_uploads_part());
-  $form['filebrowser'] = array_merge($form['filebrowser'], (array)_filebrowser_form_file_handlers_part());
+  $form['filebrowser'] += _filebrowser_form_presentation_part();
+  $form['filebrowser'] += _filebrowser_form_rights_part();
+  $form['filebrowser'] += _filebrowser_form_uploads_part();
+  $form['filebrowser'] += _filebrowser_form_file_handlers_part();
   return system_settings_form($form);
 }
\ No newline at end of file