diff --git a/libc/kernel/uapi/linux/un.h b/libc/kernel/uapi/linux/un.h
index f735c74..fefbf5b 100644
--- a/libc/kernel/uapi/linux/un.h
+++ b/libc/kernel/uapi/linux/un.h
@@ -24,4 +24,5 @@
   __kernel_sa_family_t sun_family;
   char sun_path[UNIX_PATH_MAX];
 };
+#define SIOCUNIXFILE (SIOCPROTOPRIVATE + 0)
 #endif