diff --git a/src/etc/inc/services.inc b/src/etc/inc/services.inc
index 0b3c556a0..5e5920d84 100644
--- a/src/etc/inc/services.inc
+++ b/src/etc/inc/services.inc
@@ -911,9 +911,9 @@ EOD;
 
                 if (isset($sm['ddnsupdate'])) {
                     if (($sm['ddnsdomain'] <> "") && ($sm['ddnsdomain'] != $dhcpifconf['ddnsdomain'])) {
-                        $pdnscfg .= "    ddns-domainname \"{$sm['ddnsdomain']}\";\n";
+                        $smdnscfg .= "    ddns-domainname \"{$sm['ddnsdomain']}\";\n";
                     }
-                    $pdnscfg .= "    ddns-update-style interim;\n";
+                    $smdnscfg .= "    ddns-update-style interim;\n";
                 }
 
                 if (!empty($sm['dnsserver']) && ($sm['dnsserver'][0]) && ($sm['dnsserver'][0] != $dhcpifconf['dnsserver'][0])) {