--- interfaces.php	2013-02-17 12:07:45.000000000 -0500
+++ interfaces.php.tmp	2013-02-17 12:03:00.000000000 -0500
@@ -432,7 +432,7 @@
 	/* input validation */
 	if (isset($config['dhcpd']) && isset($config['dhcpd'][$if]['enable']) && (! preg_match("/^staticv4/", $_POST['type'])))
 		$input_errors[] = gettext("The DHCP Server is active on this interface and it can be used only with a static IP configuration. Please disable the DHCP Server service on this interface first, then change the interface configuration.");
-	if (isset($config['dhcpd6']) && isset($config['dhcpd6'][$if]['enable']) && (! preg_match("/^staticv6/", $_POST['type6'])))
+	if (isset($config['dhcpdv6']) && isset($config['dhcpdv6'][$if]['enable']) && (! preg_match("/^staticv6/", $_POST['type6'])))
 		$input_errors[] = gettext("The DHCP6 Server is active on this interface and it can be used only with a static IPv6 configuration. Please disable the DHCPv6 Server service on this interface first, then change the interface configuration.");
 
 	switch(strtolower($_POST['type'])) {