diff --git a/reader/templates/reader/book_read/viewer.mjs b/reader/templates/reader/book_read/viewer.mjs
index d7a71e7e9a042638470197715067501f41c4a714..d9d94c08e90a92693c6d78cfa1e4b2f1dbf3be0d 100644
--- a/reader/templates/reader/book_read/viewer.mjs
+++ b/reader/templates/reader/book_read/viewer.mjs
@@ -829,7 +829,7 @@ const defaultOptions = {
     kind: OptionKind.WORKER
   },
   workerSrc: {
-    value: "{% static 'pdfjs/pdf.worker.js' %}",
+    value: "{% static 'pdfjs/pdf.worker.mjs' %}",
     kind: OptionKind.WORKER
   }
 };
@@ -839,7 +839,7 @@ const defaultOptions = {
     kind: OptionKind.VIEWER
   };
   defaultOptions.sandboxBundleSrc = {
-    value: "{% static 'pdfjs/pdf.sandbox.js' %}",
+    value: "{% static 'pdfjs/pdf.sandbox.mjs' %}",
     kind: OptionKind.VIEWER
   };
   defaultOptions.viewerCssTheme = {