diff --git a/testing/web-platform/tests/webcodecs/encoded-audio-chunk.any.js b/testing/web-platform/tests/webcodecs/encoded-audio-chunk.any.js
index 00589123c0501..1ada120e4d91a 100644
--- a/testing/web-platform/tests/webcodecs/encoded-audio-chunk.any.js
+++ b/testing/web-platform/tests/webcodecs/encoded-audio-chunk.any.js
@@ -38,7 +38,8 @@ test(t => {
     TypeError,
     () => chunk.copyTo(new Uint8Array(2)), 'destination is not large enough');
 
+  const detached = makeDetachedArrayBuffer();
   assert_throws_js(
     TypeError,
-    () => chunk.copyTo(makeDetachedArrayBuffer()), 'destination is detached');
+    () => chunk.copyTo(detached), 'destination is detached');
 }, 'Test copyTo() exception if destination invalid');
diff --git a/testing/web-platform/tests/webcodecs/encoded-video-chunk.any.js b/testing/web-platform/tests/webcodecs/encoded-video-chunk.any.js
index 7013175752152..0cf0d8de4408d 100644
--- a/testing/web-platform/tests/webcodecs/encoded-video-chunk.any.js
+++ b/testing/web-platform/tests/webcodecs/encoded-video-chunk.any.js
@@ -38,7 +38,8 @@ test(t => {
     TypeError,
     () => chunk.copyTo(new Uint8Array(2)), 'destination is not large enough');
 
+  const detached = makeDetachedArrayBuffer();
   assert_throws_js(
     TypeError,
-    () => chunk.copyTo(makeDetachedArrayBuffer()), 'destiation is detached');
+    () => chunk.copyTo(detached), 'destination is detached');
 }, 'Test copyTo() exception if destiation invalid');
\ No newline at end of file
diff --git a/testing/web-platform/tests/webcodecs/utils.js b/testing/web-platform/tests/webcodecs/utils.js
index 814d435666b64..2dcfefa0a0ef9 100644
--- a/testing/web-platform/tests/webcodecs/utils.js
+++ b/testing/web-platform/tests/webcodecs/utils.js
@@ -195,7 +195,8 @@ function testCanvas(ctx, width, height, expected_pixel, imageSetting, assert_com
 }
 
 function makeDetachedArrayBuffer() {
-  let buffer = new Uint8Array();
+  const buffer = new ArrayBuffer(10);
+  const view = new Uint8Array(buffer);
   new MessageChannel().port1.postMessage(buffer, [buffer]);
-  return buffer;
+  return view;
 }