diff --git a/demos/dnd-upload.html b/demos/dnd-upload.html
index 7b1ceb9..9adf40e 100644
--- a/demos/dnd-upload.html
+++ b/demos/dnd-upload.html
@@ -73,7 +73,7 @@
     debugger;
     var formData = tests.formdata ? new FormData() : null;
     for (var i = 0; i < files.length; i++) {
-      if (tests.formdata) formData.append('file', files[i]);
+      if (tests.formdata) formData.append('file' + i, files[i]);
       previewfile(files[i]);
     }