diff --git a/web/app.js b/web/app.js
index e630ac5d5..1260b9d74 100644
--- a/web/app.js
+++ b/web/app.js
@@ -1220,11 +1220,12 @@ const PDFViewerApplication = {
     const workerParams = AppOptions.getAll(OptionKind.WORKER);
     Object.assign(GlobalWorkerOptions, workerParams);
 
-    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
-      if (args.data && isPdfFile(args.filename)) {
-        this._contentDispositionFilename = args.filename;
-      }
-    } else if (args.url) {
+    if (args.data && isPdfFile(args.filename)) {
+      this._contentDispositionFilename = args.filename;
+    } else if (
+      (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) &&
+      args.url
+    ) {
       // The Firefox built-in viewer always calls `setTitleUsingUrl`, before
       // `initPassiveLoading`, and it never provides an `originalUrl` here.
       this.setTitleUsingUrl(