diff --git a/libc/kernel/uapi/linux/ipv6.h b/libc/kernel/uapi/linux/ipv6.h
index b3db9ce..757cbda 100644
--- a/libc/kernel/uapi/linux/ipv6.h
+++ b/libc/kernel/uapi/linux/ipv6.h
@@ -148,6 +148,7 @@
   DEVCONF_IOAM6_ID,
   DEVCONF_IOAM6_ID_WIDE,
   DEVCONF_NDISC_EVICT_NOCARRIER,
+  DEVCONF_ACCEPT_UNTRACKED_NA,
   DEVCONF_MAX
 };
 #endif