diff --git a/src/main/resources/static/js/downloader.js b/src/main/resources/static/js/downloader.js
index bab75025..2ccbc093 100644
--- a/src/main/resources/static/js/downloader.js
+++ b/src/main/resources/static/js/downloader.js
@@ -99,6 +99,7 @@
   async function getPDFPageCount(file) {
     try {
       const arrayBuffer = await file.arrayBuffer();
+      pdfjsLib.GlobalWorkerOptions.workerSrc = '/pdfjs-legacy/pdf.worker.mjs'
       const pdf = await pdfjsLib.getDocument({ data: arrayBuffer }).promise;
       return pdf.numPages;
     } catch (error) {