diff --git a/libc/kernel/uapi/linux/ipv6.h b/libc/kernel/uapi/linux/ipv6.h
index d07fa06..ff345a6 100644
--- a/libc/kernel/uapi/linux/ipv6.h
+++ b/libc/kernel/uapi/linux/ipv6.h
@@ -140,6 +140,7 @@
   DEVCONF_ADDR_GEN_MODE,
   DEVCONF_DISABLE_POLICY,
   DEVCONF_ACCEPT_RA_RT_INFO_MIN_PLEN,
+  DEVCONF_NDISC_TCLASS,
   DEVCONF_MAX
 };
 #endif