diff --git a/test/unit/display_utils_spec.js b/test/unit/display_utils_spec.js
index f5957e6c8e01c..eef734a836966 100644
--- a/test/unit/display_utils_spec.js
+++ b/test/unit/display_utils_spec.js
@@ -19,7 +19,7 @@ import {
   isValidFetchUrl,
   PDFDateString,
 } from "../../src/display/display_utils.js";
-import { bytesToString } from "../../src/shared/util.js";
+import { toBase64Util } from "../../src/shared/util.js";
 
 describe("display_utils", function () {
   describe("getFilenameFromUrl", function () {
@@ -179,9 +179,8 @@ describe("display_utils", function () {
     });
 
     it('gets fallback filename from query string appended to "data:" URL', function () {
-      const typedArray = new Uint8Array([1, 2, 3, 4, 5]),
-        str = bytesToString(typedArray);
-      const dataUrl = `data:application/pdf;base64,${btoa(str)}`;
+      const typedArray = new Uint8Array([1, 2, 3, 4, 5]);
+      const dataUrl = `data:application/pdf;base64,${toBase64Util(typedArray)}`;
       // Sanity check to ensure that a "data:" URL was returned.
       expect(dataUrl.startsWith("data:")).toEqual(true);