diff --git a/libc/kernel/uapi/linux/igmp.h b/libc/kernel/uapi/linux/igmp.h
index f5d1164..885b0f8 100644
--- a/libc/kernel/uapi/linux/igmp.h
+++ b/libc/kernel/uapi/linux/igmp.h
@@ -73,6 +73,7 @@
 #define IGMPV3_HOST_MEMBERSHIP_REPORT 0x22
 #define IGMP_MTRACE_RESP 0x1e
 #define IGMP_MTRACE 0x1f
+#define IGMP_MRDISC_ADV 0x30
 #define IGMP_DELAYING_MEMBER 0x01
 #define IGMP_IDLE_MEMBER 0x02
 #define IGMP_LAZY_MEMBER 0x03