diff --git a/src/dhcp6-protocol.h b/src/dhcp6-protocol.h
index 50d84a9..c4eef35 100644
--- a/src/dhcp6-protocol.h
+++ b/src/dhcp6-protocol.h
@@ -55,6 +55,7 @@
 #define OPTION6_RECONF_ACCEPT   20
 #define OPTION6_DNS_SERVER      23
 #define OPTION6_DOMAIN_SEARCH   24
+#define OPTION6_REFRESH_TIME    32
 #define OPTION6_REMOTE_ID       37
 #define OPTION6_SUBSCRIBER_ID   38
 #define OPTION6_FQDN            39