diff --git a/libc/kernel/uapi/asm-generic/socket.h b/libc/kernel/uapi/asm-generic/socket.h
index 2c99f48..6767993 100644
--- a/libc/kernel/uapi/asm-generic/socket.h
+++ b/libc/kernel/uapi/asm-generic/socket.h
@@ -99,6 +99,7 @@
 #define SO_BUSY_POLL_BUDGET 70
 #define SO_NETNS_COOKIE 71
 #define SO_BUF_LOCK 72
+#define SO_RESERVE_MEM 73
 #if __BITS_PER_LONG == 64 || defined(__x86_64__) && defined(__ILP32__)
 #define SO_TIMESTAMP SO_TIMESTAMP_OLD
 #define SO_TIMESTAMPNS SO_TIMESTAMPNS_OLD