diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 09378ea..236f537 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -533,6 +533,7 @@
 	NET_IPV6_FORCE_MLD_VERSION=17,
 	NET_IPV6_ACCEPT_RA_DEFRTR=18,
 	NET_IPV6_ACCEPT_RA_PINFO=19,
+	NET_IPV6_ACCEPT_RA_RTR_PREF=20,
 	__NET_IPV6_MAX
 };