diff --git a/interface/web/dns/form/dns_cname.tform.php b/interface/web/dns/form/dns_cname.tform.php
index 5fdf8c9b4ea00fe3718e471240ca48ae687828cb..d04c1d01aff18bf82fffe94ec213e74123684de5 100644
--- a/interface/web/dns/form/dns_cname.tform.php
+++ b/interface/web/dns/form/dns_cname.tform.php
@@ -115,7 +115,7 @@ $form["tabs"]['dns'] = array (
 			'validators' => array (  0 => array ( 'type' => 'NOTEMPTY',
 					'errmsg'=> 'data_error_empty'),
 				1 => array ( 'type' => 'REGEX',
-					'regex' => '/^[a-zA-Z0-9\.\-]{1,255}$/',
+					'regex' => '/^[a-zA-Z0-9\.\-\_]{1,255}$/',
 					'errmsg'=> 'data_error_regex'),
 			),
 			'default' => '',