diff --git a/libc/kernel/uapi/linux/mctp.h b/libc/kernel/uapi/linux/mctp.h
index b6bee11..21a9a14 100644
--- a/libc/kernel/uapi/linux/mctp.h
+++ b/libc/kernel/uapi/linux/mctp.h
@@ -20,6 +20,7 @@
 #define __UAPI_MCTP_H
 #include <linux/types.h>
 #include <linux/socket.h>
+#include <linux/netdevice.h>
 typedef __u8 mctp_eid_t;
 struct mctp_addr {
   mctp_eid_t s_addr;
@@ -33,9 +34,17 @@
   __u8 smctp_tag;
   __u8 __smctp_pad1;
 };
+struct sockaddr_mctp_ext {
+  struct sockaddr_mctp smctp_base;
+  int smctp_ifindex;
+  __u8 smctp_halen;
+  __u8 __smctp_pad0[3];
+  __u8 smctp_haddr[MAX_ADDR_LEN];
+};
 #define MCTP_NET_ANY 0x0
 #define MCTP_ADDR_NULL 0x00
 #define MCTP_ADDR_ANY 0xff
 #define MCTP_TAG_MASK 0x07
 #define MCTP_TAG_OWNER 0x08
+#define MCTP_OPT_ADDR_EXT 1
 #endif