diff --git a/static/upload.js b/static/upload.js
index 2679b46..95c7a94 100644
--- a/static/upload.js
+++ b/static/upload.js
@@ -27,6 +27,7 @@ function finishSending() {
 function sendData() {
     if (fileIndex >= files.length) {
         finishSending();
+        return;
     }
     const currentFile = files[fileIndex];
     if (byteIndex < currentFile.size) {