diff --git a/block.c b/block.c
index c40dd2c..9719649 100644
--- a/block.c
+++ b/block.c
@@ -2198,6 +2198,7 @@ int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs)
     num_reqs = multiwrite_merge(bs, reqs, num_reqs, mcb);
 
     // Run the aio requests
+    mcb->num_requests = num_reqs;
     for (i = 0; i < num_reqs; i++) {
         acb = bdrv_aio_writev(bs, reqs[i].sector, reqs[i].qiov,
             reqs[i].nb_sectors, multiwrite_cb, mcb);
@@ -2206,16 +2207,13 @@ int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs)
             // We can only fail the whole thing if no request has been
             // submitted yet. Otherwise we'll wait for the submitted AIOs to
             // complete and report the error in the callback.
-            if (mcb->num_requests == 0) {
+            if (i == 0) {
                 reqs[i].error = -EIO;
                 goto fail;
             } else {
-                mcb->num_requests++;
                 multiwrite_cb(mcb, -EIO);
                 break;
             }
-        } else {
-            mcb->num_requests++;
         }
     }