diff --git a/test/wpt/test-blob.js b/test/wpt/test-blob.js
index 0614c2d3fe36f1..0a0c16a4e3631b 100644
--- a/test/wpt/test-blob.js
+++ b/test/wpt/test-blob.js
@@ -5,11 +5,4 @@ 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 988a6270a936d6..d402d8be2f7c39 100644
--- a/test/wpt/test-broadcastchannel.js
+++ b/test/wpt/test-broadcastchannel.js
@@ -5,9 +5,4 @@ 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 901f53e00e22f0..bf54683c5c9f14 100644
--- a/test/wpt/test-encoding.js
+++ b/test/wpt/test-encoding.js
@@ -3,10 +3,4 @@ require('../common');
 const { WPTRunner } = require('../common/wpt');
 const runner = new WPTRunner('encoding');
 
-runner.setInitScript(`
-  globalThis.location ||= {};
-  const { MessageChannel } = require('worker_threads');
-  global.MessageChannel = MessageChannel;
-`);
-
 runner.runJsTests();