diff --git a/lib/web/eventsource/eventsource.js b/lib/web/eventsource/eventsource.js
index b736eb3c5f5..4c402f0e066 100644
--- a/lib/web/eventsource/eventsource.js
+++ b/lib/web/eventsource/eventsource.js
@@ -3,7 +3,7 @@
 const { pipeline } = require('node:stream')
 const { fetching } = require('../fetch')
 const { makeRequest } = require('../fetch/request')
-const { webidl, maybeMarkAsUncloneable } = require('../fetch/webidl')
+const { webidl } = require('../fetch/webidl')
 const { EventSourceStream } = require('./eventsource-stream')
 const { parseMIMEType } = require('../fetch/data-url')
 const { createFastMessageEvent } = require('../websocket/events')
@@ -109,7 +109,7 @@ class EventSource extends EventTarget {
     // 1. Let ev be a new EventSource object.
     super()
 
-    maybeMarkAsUncloneable(this)
+    webidl.util.maybeMarkAsUncloneable(this)
 
     const prefix = 'EventSource constructor'
     webidl.argumentLengthCheck(arguments, 1, prefix)
diff --git a/lib/web/fetch/formdata.js b/lib/web/fetch/formdata.js
index 918a14ed7f0..6bd57bf6572 100644
--- a/lib/web/fetch/formdata.js
+++ b/lib/web/fetch/formdata.js
@@ -2,7 +2,7 @@
 
 const { iteratorMixin } = require('./util')
 const { kEnumerableProperty } = require('../../core/util')
-const { webidl, maybeMarkAsUncloneable } = require('./webidl')
+const { webidl } = require('./webidl')
 const { File: NativeFile } = require('node:buffer')
 const nodeUtil = require('node:util')
 
@@ -14,7 +14,7 @@ class FormData {
   #state = []
 
   constructor (form) {
-    maybeMarkAsUncloneable(this)
+    webidl.util.maybeMarkAsUncloneable(this)
 
     if (form !== undefined) {
       throw webidl.errors.conversionFailed({
diff --git a/lib/web/fetch/headers.js b/lib/web/fetch/headers.js
index 7f6c2cb6d73..7e6182556ff 100644
--- a/lib/web/fetch/headers.js
+++ b/lib/web/fetch/headers.js
@@ -9,7 +9,7 @@ const {
   isValidHeaderName,
   isValidHeaderValue
 } = require('./util')
-const { webidl, maybeMarkAsUncloneable } = require('./webidl')
+const { webidl } = require('./webidl')
 const assert = require('node:assert')
 const util = require('node:util')
 
@@ -420,7 +420,7 @@ class Headers {
   #headersList
 
   constructor (init = undefined) {
-    maybeMarkAsUncloneable(this)
+    webidl.util.maybeMarkAsUncloneable(this)
 
     if (init === kConstruct) {
       return
diff --git a/lib/web/fetch/request.js b/lib/web/fetch/request.js
index 352e3a4aa43..de6f3f9a466 100644
--- a/lib/web/fetch/request.js
+++ b/lib/web/fetch/request.js
@@ -23,7 +23,7 @@ const {
   requestDuplex
 } = require('./constants')
 const { kEnumerableProperty, normalizedMethodRecordsBase, normalizedMethodRecords } = util
-const { webidl, maybeMarkAsUncloneable } = require('./webidl')
+const { webidl } = require('./webidl')
 const { URLSerializer } = require('./data-url')
 const { kConstruct } = require('../../core/symbols')
 const assert = require('node:assert')
@@ -92,7 +92,7 @@ class Request {
 
   // https://fetch.spec.whatwg.org/#dom-request
   constructor (input, init = undefined) {
-    maybeMarkAsUncloneable(this)
+    webidl.util.maybeMarkAsUncloneable(this)
 
     if (input === kConstruct) {
       return
diff --git a/lib/web/fetch/response.js b/lib/web/fetch/response.js
index 120b4f7b16a..e6b8c6a8833 100644
--- a/lib/web/fetch/response.js
+++ b/lib/web/fetch/response.js
@@ -18,7 +18,7 @@ const {
   redirectStatusSet,
   nullBodyStatus
 } = require('./constants')
-const { webidl, maybeMarkAsUncloneable } = require('./webidl')
+const { webidl } = require('./webidl')
 const { FormData } = require('./formdata')
 const { URLSerializer } = require('./data-url')
 const { kConstruct } = require('../../core/symbols')
@@ -113,7 +113,7 @@ class Response {
 
   // https://fetch.spec.whatwg.org/#dom-response
   constructor (body = null, init = undefined) {
-    maybeMarkAsUncloneable(this)
+    webidl.util.maybeMarkAsUncloneable(this)
 
     if (body === kConstruct) {
       return
diff --git a/lib/web/fetch/webidl.js b/lib/web/fetch/webidl.js
index 5cc794c5930..97922be8fa7 100644
--- a/lib/web/fetch/webidl.js
+++ b/lib/web/fetch/webidl.js
@@ -120,6 +120,12 @@ webidl.util.TypeValueToString = function (o) {
   }
 }
 
+webidl.util.maybeMarkAsUncloneable = function (target) {
+  if (markAsUncloneable !== undefined) {
+    markAsUncloneable(target)
+  }
+}
+
 // https://webidl.spec.whatwg.org/#abstract-opdef-converttoint
 webidl.util.ConvertToInt = function (V, bitLength, signedness, opts) {
   let upperBound
@@ -700,13 +706,6 @@ webidl.converters['record<ByteString, ByteString>'] = webidl.recordConverter(
 
 webidl.converters.Blob = webidl.interfaceConverter(Blob)
 
-function maybeMarkAsUncloneable (target) {
-  if (markAsUncloneable !== undefined) {
-    markAsUncloneable(target)
-  }
-}
-
 module.exports = {
-  webidl,
-  maybeMarkAsUncloneable
+  webidl
 }
diff --git a/lib/web/websocket/events.js b/lib/web/websocket/events.js
index 0c22986c87c..d12cb0388b2 100644
--- a/lib/web/websocket/events.js
+++ b/lib/web/websocket/events.js
@@ -1,6 +1,6 @@
 'use strict'
 
-const { webidl, maybeMarkAsUncloneable } = require('../fetch/webidl')
+const { webidl } = require('../fetch/webidl')
 const { kEnumerableProperty } = require('../../core/util')
 const { kConstruct } = require('../../core/symbols')
 const { MessagePort } = require('node:worker_threads')
@@ -14,7 +14,7 @@ class MessageEvent extends Event {
   constructor (type, eventInitDict = {}) {
     if (type === kConstruct) {
       super(arguments[1], arguments[2])
-      maybeMarkAsUncloneable(this)
+      webidl.util.maybeMarkAsUncloneable(this)
       return
     }
 
@@ -27,7 +27,7 @@ class MessageEvent extends Event {
     super(type, eventInitDict)
 
     this.#eventInit = eventInitDict
-    maybeMarkAsUncloneable(this)
+    webidl.util.maybeMarkAsUncloneable(this)
   }
 
   get data () {
@@ -114,7 +114,7 @@ class CloseEvent extends Event {
     super(type, eventInitDict)
 
     this.#eventInit = eventInitDict
-    maybeMarkAsUncloneable(this)
+    webidl.util.maybeMarkAsUncloneable(this)
   }
 
   get wasClean () {
diff --git a/lib/web/websocket/websocket.js b/lib/web/websocket/websocket.js
index a882932f814..9ece7b256be 100644
--- a/lib/web/websocket/websocket.js
+++ b/lib/web/websocket/websocket.js
@@ -1,6 +1,6 @@
 'use strict'
 
-const { webidl, maybeMarkAsUncloneable } = require('../fetch/webidl')
+const { webidl } = require('../fetch/webidl')
 const { URLSerializer } = require('../fetch/data-url')
 const { environmentSettingsObject } = require('../fetch/util')
 const { staticPropertyDescriptors, states, sentCloseFrameState, sendHints, opcodes } = require('./constants')
@@ -100,7 +100,7 @@ class WebSocket extends EventTarget {
   constructor (url, protocols = []) {
     super()
 
-    maybeMarkAsUncloneable(this)
+    webidl.util.maybeMarkAsUncloneable(this)
 
     const prefix = 'WebSocket constructor'
     webidl.argumentLengthCheck(arguments, 1, prefix)