diff --git a/libc/kernel/uapi/linux/btrfs.h b/libc/kernel/uapi/linux/btrfs.h
index a40e24d..08b96a3 100644
--- a/libc/kernel/uapi/linux/btrfs.h
+++ b/libc/kernel/uapi/linux/btrfs.h
@@ -420,14 +420,16 @@
 #define BTRFS_SEND_FLAG_NO_FILE_DATA 0x1
 #define BTRFS_SEND_FLAG_OMIT_STREAM_HEADER 0x2
 #define BTRFS_SEND_FLAG_OMIT_END_CMD 0x4
-#define BTRFS_SEND_FLAG_MASK (BTRFS_SEND_FLAG_NO_FILE_DATA | BTRFS_SEND_FLAG_OMIT_STREAM_HEADER | BTRFS_SEND_FLAG_OMIT_END_CMD)
+#define BTRFS_SEND_FLAG_VERSION 0x8
+#define BTRFS_SEND_FLAG_MASK (BTRFS_SEND_FLAG_NO_FILE_DATA | BTRFS_SEND_FLAG_OMIT_STREAM_HEADER | BTRFS_SEND_FLAG_OMIT_END_CMD | BTRFS_SEND_FLAG_VERSION)
 struct btrfs_ioctl_send_args {
   __s64 send_fd;
   __u64 clone_sources_count;
   __u64 __user * clone_sources;
   __u64 parent_root;
   __u64 flags;
-  __u64 reserved[4];
+  __u32 version;
+  __u8 reserved[28];
 };
 struct btrfs_ioctl_get_subvol_info_args {
   __u64 treeid;