diff --git a/libc/kernel/uapi/linux/icmpv6.h b/libc/kernel/uapi/linux/icmpv6.h
index 38c30cf..e23fbb4 100644
--- a/libc/kernel/uapi/linux/icmpv6.h
+++ b/libc/kernel/uapi/linux/icmpv6.h
@@ -106,6 +106,7 @@
 #define ICMPV6_HDR_FIELD 0
 #define ICMPV6_UNK_NEXTHDR 1
 #define ICMPV6_UNK_OPTION 2
+#define ICMPV6_HDR_INCOMP 3
 #define ICMPV6_FILTER 1
 #define ICMPV6_FILTER_BLOCK 1
 #define ICMPV6_FILTER_PASS 2