diff --git a/libc/kernel/uapi/linux/in6.h b/libc/kernel/uapi/linux/in6.h
index 8dd3238..49efe3c 100644
--- a/libc/kernel/uapi/linux/in6.h
+++ b/libc/kernel/uapi/linux/in6.h
@@ -105,6 +105,7 @@
 #define IPV6_TLV_PADN 1
 #define IPV6_TLV_ROUTERALERT 5
 #define IPV6_TLV_CALIPSO 7
+#define IPV6_TLV_IOAM 49
 #define IPV6_TLV_JUMBO 194
 #define IPV6_TLV_HAO 201
 #if __UAPI_DEF_IPV6_OPTIONS