diff --git a/test/wpt/test-blob.js b/test/wpt/test-blob.js
index 1d6871ce27933f..9027516ec619f4 100644
--- a/test/wpt/test-blob.js
+++ b/test/wpt/test-blob.js
@@ -4,11 +4,4 @@ const { WPTRunner } = require('../common/wpt');
 
 const runner = new WPTRunner('FileAPI/blob');
 
-runner.setInitScript(`
-  const { Blob } = require('buffer');
-  const { ReadableStream } = require('stream/web');
-  global.Blob = Blob;
-  global.ReadableStream = ReadableStream;
-`);
-
 runner.runJsTests();
diff --git a/test/wpt/test-broadcastchannel.js b/test/wpt/test-broadcastchannel.js
index 586343ed8221dc..6757e1429fc5c4 100644
--- a/test/wpt/test-broadcastchannel.js
+++ b/test/wpt/test-broadcastchannel.js
@@ -4,9 +4,4 @@ const { WPTRunner } = require('../common/wpt');
 
 const runner = new WPTRunner('webmessaging/broadcastchannel');
 
-runner.setInitScript(`
-  const { BroadcastChannel } = require('worker_threads');
-  global.BroadcastChannel = BroadcastChannel;
-`);
-
 runner.runJsTests();
diff --git a/test/wpt/test-encoding.js b/test/wpt/test-encoding.js
index 7aeddfefe450e8..af20760bd533d3 100644
--- a/test/wpt/test-encoding.js
+++ b/test/wpt/test-encoding.js
@@ -3,9 +3,4 @@
 const { WPTRunner } = require('../common/wpt');
 const runner = new WPTRunner('encoding');
 
-runner.setInitScript(`
-  const { MessageChannel } = require('worker_threads');
-  global.MessageChannel = MessageChannel;
-`);
-
 runner.runJsTests();