diff --git a/interface/lib/classes/validate_cron.inc.php b/interface/lib/classes/validate_cron.inc.php
index 27db600820dadecafa17223f52388d108df299b5..bc768b4da29ec40fe05767f5b3431632ddee332c 100644
--- a/interface/lib/classes/validate_cron.inc.php
+++ b/interface/lib/classes/validate_cron.inc.php
@@ -52,7 +52,7 @@ class validate_cron {
 
 			if($parsed["scheme"] != "http" && $parsed["scheme"] != "https") return $this->get_error($validator['errmsg']);
 
-			if(preg_match("'^([a-z0-9][a-z0-9\-]{0,62}\.)+([A-Za-z0-9\-]{2,30})$'i", $parsed["host"]) == false) return $this->get_error($validator['errmsg']);
+			if(preg_match("'^([a-z0-9][a-z0-9_\-]{0,62}\.)+([A-Za-z0-9\-]{2,30})$'i", $parsed["host"]) == false) return $this->get_error($validator['errmsg']);
 		}
 	}