diff --git a/libc/kernel/uapi/linux/btrfs.h b/libc/kernel/uapi/linux/btrfs.h
index 0dae543..14cd6e8 100644
--- a/libc/kernel/uapi/linux/btrfs.h
+++ b/libc/kernel/uapi/linux/btrfs.h
@@ -458,6 +458,7 @@
 #define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_RESIZE _IOW(BTRFS_IOCTL_MAGIC, 3, struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_SCAN_DEV _IOW(BTRFS_IOCTL_MAGIC, 4, struct btrfs_ioctl_vol_args)
+#define BTRFS_IOC_FORGET_DEV _IOW(BTRFS_IOCTL_MAGIC, 5, struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_TRANS_START _IO(BTRFS_IOCTL_MAGIC, 6)
 #define BTRFS_IOC_TRANS_END _IO(BTRFS_IOCTL_MAGIC, 7)
 #define BTRFS_IOC_SYNC _IO(BTRFS_IOCTL_MAGIC, 8)