diff --git a/src/main_thread/decrypt/__tests__/__global__/utils.ts b/src/main_thread/decrypt/__tests__/__global__/utils.ts
index 3e27d7eb92f..5c1e23fbf22 100644
--- a/src/main_thread/decrypt/__tests__/__global__/utils.ts
+++ b/src/main_thread/decrypt/__tests__/__global__/utils.ts
@@ -515,5 +515,11 @@ export function formatFakeChallengeFromInitData(
 ): Uint8Array {
   const initDataAB = initData instanceof ArrayBuffer ? initData : initData.buffer;
   const objChallenge = [initDataType, bytesToBase64(new Uint8Array(initDataAB))];
-  return strToUtf8(JSON.stringify(objChallenge));
+  let data = strToUtf8(JSON.stringify(objChallenge));
+  // Work-around some testing environment issue
+  // see https://github.com/vitest-dev/vitest/issues/4043
+  if (!(data instanceof Uint8Array)) {
+    data = new Uint8Array(data);
+  }
+  return data;
 }
diff --git a/src/parsers/texttracks/ttml/html/__tests__/__global__/html_ttml_parser.test.test.ts b/src/parsers/texttracks/ttml/html/__tests__/__global__/html_ttml_parser.test.ts
similarity index 89%
rename from src/parsers/texttracks/ttml/html/__tests__/__global__/html_ttml_parser.test.test.ts
rename to src/parsers/texttracks/ttml/html/__tests__/__global__/html_ttml_parser.test.ts
index ad36a6ecbc7..ef3b19c9922 100644
--- a/src/parsers/texttracks/ttml/html/__tests__/__global__/html_ttml_parser.test.test.ts
+++ b/src/parsers/texttracks/ttml/html/__tests__/__global__/html_ttml_parser.test.ts
@@ -162,12 +162,24 @@ describe("Global TTML HTML parsing tests", () => {
       return currTextNodes;
     }
     let nbTextNodes = 0;
-    const textNodes = findTextNodes(res[6].element);
-    for (let i = 0; i < textNodes.length; i++) {
-      const parentElement = textNodes[i].parentElement;
-      if (parentElement !== null) {
-        expect(globalScope.getComputedStyle(parentElement).color).toEqual("yellow");
-        nbTextNodes++;
+    {
+      const textNodes = findTextNodes(res[5].element);
+      for (let i = 0; i < textNodes.length; i++) {
+        const parentElement = textNodes[i].parentElement;
+        if (parentElement !== null) {
+          expect(globalScope.getComputedStyle(parentElement).color).toEqual("yellow");
+          nbTextNodes++;
+        }
+      }
+    }
+    {
+      const textNodes = findTextNodes(res[6].element);
+      for (let i = 0; i < textNodes.length; i++) {
+        const parentElement = textNodes[i].parentElement;
+        if (parentElement !== null) {
+          expect(globalScope.getComputedStyle(parentElement).color).toEqual("white");
+          nbTextNodes++;
+        }
       }
     }
     expect(nbTextNodes).toBeGreaterThanOrEqual(1);