diff --git a/block/parallels.c b/block/parallels.c
index 6bf93753e8..4173b3fb9d 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -687,7 +687,8 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
     if (local_err != NULL) {
         goto fail_options;
     }
-    if (!bdrv_has_zero_init(bs->file->bs) ||
+
+    if (!(flags & BDRV_O_RESIZE) || !bdrv_has_zero_init(bs->file->bs) ||
             bdrv_truncate(bs->file, bdrv_getlength(bs->file->bs)) != 0) {
         s->prealloc_mode = PRL_PREALLOC_MODE_FALLOCATE;
     }