diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index e2c5a7072aca..d128d238e1da 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -8548,6 +8548,8 @@ static int check_reshape(struct mddev *mddev)
 		return 0; /* nothing to do */
 	if (has_failed(conf))
 		return -EINVAL;
+	if (!mddev->new_chunk_sectors)
+		return -EINVAL;
 	if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
 		/* We might be able to shrink, but the devices must
 		 * be made bigger first.
@@ -8591,6 +8593,9 @@ static int raid5_start_reshape(struct mddev *mddev)
 	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
 		return -EBUSY;
 
+	if (!mddev->new_chunk_sectors)
+		return -EINVAL;
+
 	if (!check_stripe_cache(mddev))
 		return -ENOSPC;