diff --git a/ioctl.h b/ioctl.h
index a7235c00..dafb756b 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -569,6 +569,38 @@ struct btrfs_ioctl_received_subvol_args {
 };
 BUILD_ASSERT(sizeof(struct btrfs_ioctl_received_subvol_args) == 200);
 
+/*
+ * If we have a 32-bit userspace and 64-bit kernel, then the UAPI
+ * structures are incorrect, as the timespec structure from userspace
+ * is 4 bytes too small. We define these alternatives here for backward
+ * compatibility, the kernel understands both values.
+ */
+
+/*
+ * Structure size is different on 32bit and 64bit, has some padding if the
+ * structure is embedded. Packing makes sure the size is same on both, but will
+ * be misaligned on 64bit.
+ *
+ * NOTE: do not use in your code, this is for testing only
+ */
+struct btrfs_ioctl_timespec_32 {
+	__u64 sec;
+	__u32 nsec;
+} __attribute__ ((__packed__));
+
+struct btrfs_ioctl_received_subvol_args_32 {
+	char	uuid[BTRFS_UUID_SIZE];	/* in */
+	__u64	stransid;		/* in */
+	__u64	rtransid;		/* out */
+	struct btrfs_ioctl_timespec_32 stime; /* in */
+	struct btrfs_ioctl_timespec_32 rtime; /* out */
+	__u64	flags;			/* in */
+	__u64	reserved[16];		/* in */
+} __attribute__ ((__packed__));
+BUILD_ASSERT(sizeof(struct btrfs_ioctl_received_subvol_args_32) == 192);
+
+#define BTRFS_IOC_SET_RECEIVED_SUBVOL_32_COMPAT_DEFINED 1
+
 /*
  * Caller doesn't want file data in the send stream, even if the
  * search of clone sources doesn't find an extent. UPDATE_EXTENT
@@ -723,6 +755,12 @@ static inline char *btrfs_err_str(enum btrfs_err_code err_code)
 					struct btrfs_ioctl_logical_ino_args)
 #define BTRFS_IOC_SET_RECEIVED_SUBVOL _IOWR(BTRFS_IOCTL_MAGIC, 37, \
 				struct btrfs_ioctl_received_subvol_args)
+
+#ifdef BTRFS_IOC_SET_RECEIVED_SUBVOL_32_COMPAT_DEFINED
+#define BTRFS_IOC_SET_RECEIVED_SUBVOL_32 _IOWR(BTRFS_IOCTL_MAGIC, 37, \
+				struct btrfs_ioctl_received_subvol_args_32)
+#endif
+
 #define BTRFS_IOC_SEND _IOW(BTRFS_IOCTL_MAGIC, 38, struct btrfs_ioctl_send_args)
 #define BTRFS_IOC_DEVICES_READY _IOR(BTRFS_IOCTL_MAGIC, 39, \
 				     struct btrfs_ioctl_vol_args)