diff --git a/blockdev.c b/blockdev.c
index 58d7570932..72f5347df5 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1859,7 +1859,7 @@ static void blockdev_backup_prepare(BlkActionState *common, Error **errp)
     assert(common->action->type == TRANSACTION_ACTION_KIND_BLOCKDEV_BACKUP);
     backup = common->action->u.blockdev_backup.data;
 
-    bs = qmp_get_root_bs(backup->device, errp);
+    bs = bdrv_lookup_bs(backup->device, backup->device, errp);
     if (!bs) {
         return;
     }
@@ -3517,7 +3517,7 @@ BlockJob *do_blockdev_backup(BlockdevBackup *backup, JobTxn *txn,
         backup->compress = false;
     }
 
-    bs = qmp_get_root_bs(backup->device, errp);
+    bs = bdrv_lookup_bs(backup->device, backup->device, errp);
     if (!bs) {
         return NULL;
     }