diff --git a/nbd/client.c b/nbd/client.c
index 7db4301d292949e9a2cb215cd43a93377efa52df..ffb0743bcecf8dcb0ff6f97c117fbbe3d0545849 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -90,20 +90,21 @@ static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
  * the amount of bytes consumed. */
 static ssize_t drop_sync(QIOChannel *ioc, size_t size)
 {
-    ssize_t ret, dropped = size;
+    ssize_t ret = 0;
     char small[1024];
     char *buffer;
 
     buffer = sizeof(small) < size ? small : g_malloc(MIN(65536, size));
     while (size > 0) {
-        ret = read_sync(ioc, buffer, MIN(65536, size));
-        if (ret < 0) {
+        ssize_t count = read_sync(ioc, buffer, MIN(65536, size));
+
+        if (count <= 0) {
             goto cleanup;
         }
-        assert(ret <= size);
-        size -= ret;
+        assert(count <= size);
+        size -= count;
+        ret += count;
     }
-    ret = dropped;
 
  cleanup:
     if (buffer != small) {