diff --git a/index.php b/index.php
index 718dd93..1456fc7 100644
--- a/index.php
+++ b/index.php
@@ -35,7 +35,7 @@ header("Preved: Krosavcheg!");
 $forum_version = 'SMF 1.0.8';
 
 # some ugly anti-bot shit:
-if ($_SERVER['HTTP_USER_AGENT'] == "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1;)") {
+if (isset ($_SERVER['HTTP_USER_AGENT']) AND $_SERVER['HTTP_USER_AGENT'] == "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1;)") {
 	header("Location: http://natribu.org"); die;
 }