diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index 59cbae1..3b401f2 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -111,6 +111,7 @@
 #define PIDFD_SELF_THREAD_GROUP		-10001 /* Current thread group leader. */
 
 #define FD_PIDFS_ROOT			-10002 /* Root of the pidfs filesystem */
+#define FD_NSFS_ROOT			-10003 /* Root of the nsfs filesystem */
 #define FD_INVALID			-10009 /* Invalid file descriptor: -10000 - EBADF = -10009 */
 
 /* Generic flags for the *at(2) family of syscalls. */