diff --git a/libc/kernel/uapi/asm-generic/socket.h b/libc/kernel/uapi/asm-generic/socket.h
index 6926187..1a321bf 100644
--- a/libc/kernel/uapi/asm-generic/socket.h
+++ b/libc/kernel/uapi/asm-generic/socket.h
@@ -101,6 +101,7 @@
 #define SO_BUF_LOCK 72
 #define SO_RESERVE_MEM 73
 #define SO_TXREHASH 74
+#define SO_RCVMARK 75
 #if __BITS_PER_LONG == 64 || defined(__x86_64__) && defined(__ILP32__)
 #define SO_TIMESTAMP SO_TIMESTAMP_OLD
 #define SO_TIMESTAMPNS SO_TIMESTAMPNS_OLD