diff --git a/libc/kernel/uapi/linux/ipv6.h b/libc/kernel/uapi/linux/ipv6.h
index 7cd6cb0..438cacc 100644
--- a/libc/kernel/uapi/linux/ipv6.h
+++ b/libc/kernel/uapi/linux/ipv6.h
@@ -143,6 +143,7 @@
   DEVCONF_ACCEPT_RA_RT_INFO_MIN_PLEN,
   DEVCONF_NDISC_TCLASS,
   DEVCONF_RPL_SEG_ENABLED,
+  DEVCONF_RA_DEFRTR_METRIC,
   DEVCONF_MAX
 };
 #endif