diff --git a/lib/internal/webstreams/transformstream.js b/lib/internal/webstreams/transformstream.js
index 6e119bde63bb2f..991033ea8423a3 100644
--- a/lib/internal/webstreams/transformstream.js
+++ b/lib/internal/webstreams/transformstream.js
@@ -368,6 +368,7 @@ function initializeTransformStream(
     close() {
       return transformStreamDefaultSinkCloseAlgorithm(stream);
     },
+    __proto__: null
   }, {
     highWaterMark: writableHighWaterMark,
     size: writableSizeAlgorithm,
@@ -382,6 +383,7 @@ function initializeTransformStream(
       transformStreamErrorWritableAndUnblockWrite(stream, reason);
       return PromiseResolve();
     },
+    __proto__: null,
   }, {
     highWaterMark: readableHighWaterMark,
     size: readableSizeAlgorithm,
diff --git a/test/parallel/test-whatwg-transformstream.js b/test/parallel/test-whatwg-transformstream.js
index 0cbc76cc4ce8c0..b8779152c7e68b 100644
--- a/test/parallel/test-whatwg-transformstream.js
+++ b/test/parallel/test-whatwg-transformstream.js
@@ -186,3 +186,18 @@ class Source {
     inspect(controller, { depth: 0 }),
     /TransformStreamDefaultController \[/);
 }
+
+{
+  Object.defineProperty(Object.prototype, 'type', {
+    get: common.mustNotCall()
+  });
+
+  new TransformStream({
+    transform(chunk, controller) {
+      controller.enqueue(chunk);
+    },
+    flush(controller) {
+      controller.terminate();
+    }
+  });
+}