diff --git a/block/iscsi.c b/block/iscsi.c
index b2b4e5d2a9c428ca5e5060a19d3af990e9cea3c5..8bc5f7e30526e27327d638c902f064c50ce555de 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -1048,7 +1048,9 @@ coroutine_fn iscsi_co_pdiscard(BlockDriverState *bs, int64_t offset, int count)
     struct IscsiTask iTask;
     struct unmap_list list;
 
-    assert(is_byte_request_lun_aligned(offset, count, iscsilun));
+    if (!is_byte_request_lun_aligned(offset, count, iscsilun)) {
+        return -ENOTSUP;
+    }
 
     if (!iscsilun->lbp.lbpu) {
         /* UNMAP is not supported by the target */
diff --git a/block/qcow2.c b/block/qcow2.c
index 497df0f639c8b6594da94655143615f331ef682a..3a80be041118d2c1b224bae6a825839d41c629ed 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2486,6 +2486,11 @@ static coroutine_fn int qcow2_co_pdiscard(BlockDriverState *bs,
     int ret;
     BDRVQcow2State *s = bs->opaque;
 
+    if (!QEMU_IS_ALIGNED(offset | count, s->cluster_size)) {
+        assert(count < s->cluster_size);
+        return -ENOTSUP;
+    }
+
     qemu_co_mutex_lock(&s->lock);
     ret = qcow2_discard_clusters(bs, offset, count >> BDRV_SECTOR_BITS,
                                  QCOW2_DISCARD_REQUEST, false);
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 66e1cb2b2dd140b944d512f0dcebe93c034113b1..314b470cbab4f4b8668387f67a73fa5194c7570d 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -2820,8 +2820,9 @@ static coroutine_fn int sd_co_pdiscard(BlockDriverState *bs, int64_t offset,
     iov.iov_len = sizeof(zero);
     discard_iov.iov = &iov;
     discard_iov.niov = 1;
-    assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
-    assert((count & (BDRV_SECTOR_SIZE - 1)) == 0);
+    if (!QEMU_IS_ALIGNED(offset | count, BDRV_SECTOR_SIZE)) {
+        return -ENOTSUP;
+    }
     acb = sd_aio_setup(bs, &discard_iov, offset >> BDRV_SECTOR_BITS,
                        count >> BDRV_SECTOR_BITS);
     acb->aiocb_type = AIOCB_DISCARD_OBJ;