diff --git a/block/sheepdog.c b/block/sheepdog.c
index 2eb61938ff..739e6dee30 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -1654,6 +1654,7 @@ static int sd_open(BlockDriverState *bs, QDict *options, int flags,
     memcpy(&s->inode, buf, sizeof(s->inode));
 
     bs->total_sectors = s->inode.vdi_size / BDRV_SECTOR_SIZE;
+    bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
     pstrcpy(s->name, sizeof(s->name), vdi);
     qemu_co_mutex_init(&s->lock);
     qemu_co_mutex_init(&s->queue_lock);