diff --git a/config/app.php.txt b/config/app.php.txt
index 87bb98e..9880af4 100644
--- a/config/app.php.txt
+++ b/config/app.php.txt
@@ -21,6 +21,6 @@ define('CRAWL_IMAGE', false); // @TODO
 define('CRAWL_PAGE_LIMIT', 10);
 define('CRAWL_PAGE_SECONDS_OFFSET', 3600);
 
-define('CRAWL_URL_REGEXP', '/^.*$/ui');
+define('CRAWL_URL_REGEXP', '/^.*$/ui'); // ipv6 only '/^http:\/\/\[[\w:]+\].*$/ui'
 
 define('CRAWL_META_ONLY', false);