diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 1a19c962f86..f4f3edcdaf8 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1483,7 +1483,7 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 		 * very different from resync
 		 */
 		return -EBUSY;
-	if (!enough(conf, -1))
+	if (rdev->saved_raid_disk < 0 && !enough(conf, -1))
 		return -EINVAL;
 
 	if (rdev->raid_disk >= 0)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 99b2bbf8b5d..d38d235cc39 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5361,7 +5361,7 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 	if (mddev->recovery_disabled == conf->recovery_disabled)
 		return -EBUSY;
 
-	if (has_failed(conf))
+	if (rdev->saved_raid_disk < 0 && has_failed(conf))
 		/* no point adding a device */
 		return -EINVAL;