diff --git a/etc/inc/services.inc b/etc/inc/services.inc
index 271b3d12b6..e6fcb3663b 100644
--- a/etc/inc/services.inc
+++ b/etc/inc/services.inc
@@ -679,7 +679,7 @@ function services_dhcpdv6_configure() {
 			/* determine possible prefix length */
 			switch($trackcfg['ipaddrv6']) {
 				case "6to4":
-					$pdlen = 48;
+					$pdlen = 16;
 					break;
 				case "6rd":
 					$rd6plen = explode("/", $rd6cfg['prefix-6rd']);