diff --git a/block/io.c b/block/io.c
index 1eb2b2bddc..7e4cb74cf4 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1565,10 +1565,12 @@ static bool bdrv_init_padding(BlockDriverState *bs,
         pad->tail = align - pad->tail;
     }
 
-    if ((!pad->head && !pad->tail) || !bytes) {
+    if (!pad->head && !pad->tail) {
         return false;
     }
 
+    assert(bytes); /* Nothing good in aligning zero-length requests */
+
     sum = pad->head + bytes + pad->tail;
     pad->buf_len = (sum > align && pad->head && pad->tail) ? 2 * align : align;
     pad->buf = qemu_blockalign(bs, pad->buf_len);
@@ -1706,6 +1708,18 @@ int coroutine_fn bdrv_co_preadv_part(BdrvChild *child,
         return ret;
     }
 
+    if (bytes == 0 && !QEMU_IS_ALIGNED(offset, bs->bl.request_alignment)) {
+        /*
+         * Aligning zero request is nonsense. Even if driver has special meaning
+         * of zero-length (like qcow2_co_pwritev_compressed_part), we can't pass
+         * it to driver due to request_alignment.
+         *
+         * Still, no reason to return an error if someone do unaligned
+         * zero-length read occasionally.
+         */
+        return 0;
+    }
+
     bdrv_inc_in_flight(bs);
 
     /* Don't do copy-on-read if we read data before write operation */
@@ -2116,6 +2130,18 @@ int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child,
         return -ENOTSUP;
     }
 
+    if (bytes == 0 && !QEMU_IS_ALIGNED(offset, bs->bl.request_alignment)) {
+        /*
+         * Aligning zero request is nonsense. Even if driver has special meaning
+         * of zero-length (like qcow2_co_pwritev_compressed_part), we can't pass
+         * it to driver due to request_alignment.
+         *
+         * Still, no reason to return an error if someone do unaligned
+         * zero-length write occasionally.
+         */
+        return 0;
+    }
+
     bdrv_inc_in_flight(bs);
     /*
      * Align write if necessary by performing a read-modify-write cycle.