diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index af61d92..736ed91 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -556,6 +556,7 @@
 	NET_IPV6_ACCEPT_RA_RTR_PREF=20,
 	NET_IPV6_RTR_PROBE_INTERVAL=21,
 	NET_IPV6_ACCEPT_RA_RT_INFO_MAX_PLEN=22,
+	NET_IPV6_PROXY_NDP=23,
 	__NET_IPV6_MAX
 };