Index: units/helpers/site_helper.php
===================================================================
--- units/helpers/site_helper.php	(revision 14975)
+++ units/helpers/site_helper.php	(working copy)
@@ -117,16 +117,16 @@
 
 			foreach ($site_domains as $id => $site_domain) {
 				if ( in_array($field, $name_fields) ) {
-					if (!$site_domain[$field . 'UsesRegExp']) {
+					if ( !$site_domain[$field . 'UsesRegExp'] ) {
 						// not regular expression -> escape manually
 						$site_domain[$field] = preg_quote($site_domain[$field], '/');
 					}
 
-					if (preg_match('/^' . $site_domain[$field] . ($field == 'DomainName' ? '$' : '') . '/', $value)) {
+					if ( $site_domain[$field] && preg_match('/^' . $site_domain[$field] . ($field == 'DomainName' ? '$' : '') . '/', $value) ) {
 						return $id;
 					}
 				}
-				elseif ($site_domain[$field] == $value) {
+				elseif ( $site_domain[$field] == $value ) {
 					return $id;
 				}
 			}