diff --git a/lib/fetch/formdata.js b/lib/fetch/formdata.js
index add64aa9226..80df2b8f399 100644
--- a/lib/fetch/formdata.js
+++ b/lib/fetch/formdata.js
@@ -1,6 +1,6 @@
 'use strict'
 
-const { isBlobLike, makeIterator } = require('./util')
+const { isBlobLike, iteratorMixin } = require('./util')
 const { kState } = require('./symbols')
 const { kEnumerableProperty } = require('../core/util')
 const { File: UndiciFile, FileLike, isFileLike } = require('./file')
@@ -154,62 +154,9 @@ class FormData {
       this[kState].push(entry)
     }
   }
-
-  entries () {
-    webidl.brandCheck(this, FormData)
-
-    return makeIterator(
-      () => this[kState],
-      'FormData',
-      'key+value',
-      'name', 'value'
-    )
-  }
-
-  keys () {
-    webidl.brandCheck(this, FormData)
-
-    return makeIterator(
-      () => this[kState],
-      'FormData',
-      'key',
-      'name', 'value'
-    )
-  }
-
-  values () {
-    webidl.brandCheck(this, FormData)
-
-    return makeIterator(
-      () => this[kState],
-      'FormData',
-      'value',
-      'name', 'value'
-    )
-  }
-
-  /**
-   * @param {(value: string, key: string, self: FormData) => void} callbackFn
-   * @param {unknown} thisArg
-   */
-  forEach (callbackFn, thisArg = globalThis) {
-    webidl.brandCheck(this, FormData)
-
-    webidl.argumentLengthCheck(arguments, 1, { header: 'FormData.forEach' })
-
-    if (typeof callbackFn !== 'function') {
-      throw new TypeError(
-        "Failed to execute 'forEach' on 'FormData': parameter 1 is not of type 'Function'."
-      )
-    }
-
-    for (const [key, value] of this) {
-      callbackFn.call(thisArg, value, key, this)
-    }
-  }
 }
 
-FormData.prototype[Symbol.iterator] = FormData.prototype.entries
+iteratorMixin('FormData', FormData, kState, 'name', 'value')
 
 Object.defineProperties(FormData.prototype, {
   append: kEnumerableProperty,
@@ -218,11 +165,6 @@ Object.defineProperties(FormData.prototype, {
   getAll: kEnumerableProperty,
   has: kEnumerableProperty,
   set: kEnumerableProperty,
-  entries: kEnumerableProperty,
-  keys: kEnumerableProperty,
-  values: kEnumerableProperty,
-  forEach: kEnumerableProperty,
-  [Symbol.iterator]: { enumerable: false },
   [Symbol.toStringTag]: {
     value: 'FormData',
     configurable: true
diff --git a/lib/fetch/headers.js b/lib/fetch/headers.js
index 504942edc6e..43860c5d98a 100644
--- a/lib/fetch/headers.js
+++ b/lib/fetch/headers.js
@@ -6,7 +6,7 @@ const { kHeadersList, kConstruct } = require('../core/symbols')
 const { kGuard } = require('./symbols')
 const { kEnumerableProperty } = require('../core/util')
 const {
-  makeIterator,
+  iteratorMixin,
   isValidHeaderName,
   isValidHeaderValue
 } = require('./util')
@@ -504,59 +504,6 @@ class Headers {
     return headers
   }
 
-  keys () {
-    webidl.brandCheck(this, Headers)
-
-    return makeIterator(
-      () => this[kHeadersSortedMap],
-      'Headers',
-      'key',
-      0, 1
-    )
-  }
-
-  values () {
-    webidl.brandCheck(this, Headers)
-
-    return makeIterator(
-      () => this[kHeadersSortedMap],
-      'Headers',
-      'value',
-      0, 1
-    )
-  }
-
-  entries () {
-    webidl.brandCheck(this, Headers)
-
-    return makeIterator(
-      () => this[kHeadersSortedMap],
-      'Headers',
-      'key+value',
-      0, 1
-    )
-  }
-
-  /**
-   * @param {(value: string, key: string, self: Headers) => void} callbackFn
-   * @param {unknown} thisArg
-   */
-  forEach (callbackFn, thisArg = globalThis) {
-    webidl.brandCheck(this, Headers)
-
-    webidl.argumentLengthCheck(arguments, 1, { header: 'Headers.forEach' })
-
-    if (typeof callbackFn !== 'function') {
-      throw new TypeError(
-        "Failed to execute 'forEach' on 'Headers': parameter 1 is not of type 'Function'."
-      )
-    }
-
-    for (const [key, value] of this) {
-      callbackFn.call(thisArg, value, key, this)
-    }
-  }
-
   [Symbol.for('nodejs.util.inspect.custom')] () {
     webidl.brandCheck(this, Headers)
 
@@ -564,7 +511,7 @@ class Headers {
   }
 }
 
-Headers.prototype[Symbol.iterator] = Headers.prototype.entries
+iteratorMixin('Headers', Headers, kHeadersSortedMap, 0, 1)
 
 Object.defineProperties(Headers.prototype, {
   append: kEnumerableProperty,
@@ -573,11 +520,6 @@ Object.defineProperties(Headers.prototype, {
   has: kEnumerableProperty,
   set: kEnumerableProperty,
   getSetCookie: kEnumerableProperty,
-  keys: kEnumerableProperty,
-  values: kEnumerableProperty,
-  entries: kEnumerableProperty,
-  forEach: kEnumerableProperty,
-  [Symbol.iterator]: { enumerable: false },
   [Symbol.toStringTag]: {
     value: 'Headers',
     configurable: true
diff --git a/lib/fetch/util.js b/lib/fetch/util.js
index c5a6b46b170..82e96ec9acd 100644
--- a/lib/fetch/util.js
+++ b/lib/fetch/util.js
@@ -6,9 +6,10 @@ const { redirectStatusSet, referrerPolicySet: referrerPolicyTokens, badPortsSet
 const { getGlobalOrigin } = require('./global')
 const { collectASequenceOfCodePoints, collectAnHTTPQuotedString, removeChars, parseMIMEType } = require('./dataURL')
 const { performance } = require('node:perf_hooks')
-const { isBlobLike, toUSVString, ReadableStreamFrom, isValidHTTPToken } = require('../core/util')
+const { isBlobLike, ReadableStreamFrom, isValidHTTPToken } = require('../core/util')
 const assert = require('node:assert')
 const { isUint8Array } = require('util/types')
+const { webidl } = require('./webidl')
 
 // https://nodejs.org/api/crypto.html#determining-if-crypto-support-is-unavailable
 /** @type {import('crypto')|undefined} */
@@ -739,35 +740,40 @@ const esIteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf([][Symbo
 
 /**
  * @see https://webidl.spec.whatwg.org/#dfn-iterator-prototype-object
- * @param {() => unknown} iterator
  * @param {string} name name of the instance
- * @param {'key'|'value'|'key+value'} kind
+ * @param {symbol} kInternalIterator
  * @param {string | number} [keyIndex]
  * @param {string | number} [valueIndex]
  */
-function makeIterator (iterator, name, kind, keyIndex = 0, valueIndex = 1) {
-  const object = {
-    index: 0,
-    kind,
-    target: iterator
-  }
-  // The [[Prototype]] internal slot of an iterator prototype object must be %IteratorPrototype%.
-  const iteratorObject = Object.create(esIteratorPrototype)
+function createIterator (name, kInternalIterator, keyIndex = 0, valueIndex = 1) {
+  class FastIterableIterator {
+    /** @type {any} */
+    #target
+    /** @type {'key' | 'value' | 'key+value'} */
+    #kind
+    /** @type {number} */
+    #index
+
+    /**
+     * @see https://webidl.spec.whatwg.org/#dfn-default-iterator-object
+     * @param {unknown} target
+     * @param {'key' | 'value' | 'key+value'} kind
+     */
+    constructor (target, kind) {
+      this.#target = target
+      this.#kind = kind
+      this.#index = 0
+    }
 
-  Object.defineProperty(iteratorObject, 'next', {
-    value: function next () {
+    next () {
       // 1. Let interface be the interface for which the iterator prototype object exists.
-
       // 2. Let thisValue be the this value.
-
       // 3. Let object be ? ToObject(thisValue).
-
       // 4. If object is a platform object, then perform a security
       //    check, passing:
-
       // 5. If object is not a default iterator object for interface,
       //    then throw a TypeError.
-      if (Object.getPrototypeOf(this) !== iteratorObject) {
+      if (typeof this !== 'object' || this === null || !(#target in this)) {
         throw new TypeError(
           `'next' called on an object that does not implement interface ${name} Iterator.`
         )
@@ -776,8 +782,8 @@ function makeIterator (iterator, name, kind, keyIndex = 0, valueIndex = 1) {
       // 6. Let index be object’s index.
       // 7. Let kind be object’s kind.
       // 8. Let values be object’s target's value pairs to iterate over.
-      const { index, kind, target } = object
-      const values = target()
+      const index = this.#index
+      const values = this.#target[kInternalIterator]
 
       // 9. Let len be the length of values.
       const len = values.length
@@ -785,17 +791,25 @@ function makeIterator (iterator, name, kind, keyIndex = 0, valueIndex = 1) {
       // 10. If index is greater than or equal to len, then return
       //     CreateIterResultObject(undefined, true).
       if (index >= len) {
-        return { value: undefined, done: true }
+        return {
+          value: undefined,
+          done: true
+        }
       }
+
       // 11. Let pair be the entry in values at index index.
       const { [keyIndex]: key, [valueIndex]: value } = values[index]
+
       // 12. Set object’s index to index + 1.
-      object.index = index + 1
+      this.#index = index + 1
+
       // 13. Return the iterator result for pair and kind.
+
       // https://webidl.spec.whatwg.org/#iterator-result
+
       // 1. Let result be a value determined by the value of kind:
       let result
-      switch (kind) {
+      switch (this.#kind) {
         case 'key':
           // 1. Let idlKey be pair’s key.
           // 2. Let key be the result of converting idlKey to an
@@ -824,29 +838,108 @@ function makeIterator (iterator, name, kind, keyIndex = 0, valueIndex = 1) {
           result = [key, value]
           break
       }
+
       // 2. Return CreateIterResultObject(result, false).
       return {
         value: result,
         done: false
       }
+    }
+  }
+
+  // https://webidl.spec.whatwg.org/#dfn-iterator-prototype-object
+  // @ts-ignore
+  delete FastIterableIterator.prototype.constructor
+
+  Object.setPrototypeOf(FastIterableIterator.prototype, esIteratorPrototype)
+
+  Object.defineProperties(FastIterableIterator.prototype, {
+    [Symbol.toStringTag]: {
+      writable: false,
+      enumerable: false,
+      configurable: true,
+      value: `${name} Iterator`
     },
-    writable: true,
-    enumerable: true,
-    configurable: true
+    next: { writable: true, enumerable: true, configurable: true }
   })
 
-  // The class string of an iterator prototype object for a given interface is the
-  // result of concatenating the identifier of the interface and the string " Iterator".
-  Object.defineProperty(iteratorObject, Symbol.toStringTag, {
-    value: `${name} Iterator`,
-    writable: false,
-    enumerable: false,
-    configurable: true
-  })
+  /**
+   * @param {unknown} target
+   * @param {'key' | 'value' | 'key+value'} kind
+   * @returns {IterableIterator<any>}
+   */
+  return function (target, kind) {
+    return new FastIterableIterator(target, kind)
+  }
+}
 
-  // esIteratorPrototype needs to be the prototype of iteratorObject
-  // which is the prototype of an empty object. Yes, it's confusing.
-  return Object.create(iteratorObject)
+/**
+ * @see https://webidl.spec.whatwg.org/#dfn-iterator-prototype-object
+ * @param {string} name name of the instance
+ * @param {any} object class
+ * @param {symbol} kInternalIterator
+ * @param {string | number} [keyIndex]
+ * @param {string | number} [valueIndex]
+ */
+function iteratorMixin (name, object, kInternalIterator, keyIndex = 0, valueIndex = 1) {
+  const makeIterator = createIterator(name, kInternalIterator, keyIndex, valueIndex)
+
+  const properties = {
+    keys: {
+      writable: true,
+      enumerable: true,
+      configurable: true,
+      value: function keys () {
+        webidl.brandCheck(this, object)
+        return makeIterator(this, 'key')
+      }
+    },
+    values: {
+      writable: true,
+      enumerable: true,
+      configurable: true,
+      value: function values () {
+        webidl.brandCheck(this, object)
+        return makeIterator(this, 'value')
+      }
+    },
+    entries: {
+      writable: true,
+      enumerable: true,
+      configurable: true,
+      value: function entries () {
+        webidl.brandCheck(this, object)
+        return makeIterator(this, 'key+value')
+      }
+    },
+    forEach: {
+      writable: true,
+      enumerable: true,
+      configurable: true,
+      value: function forEach (callbackfn, thisArg = globalThis) {
+        webidl.brandCheck(this, object)
+        webidl.argumentLengthCheck(arguments, 1, { header: `${name}.forEach` })
+        if (typeof callbackfn !== 'function') {
+          throw new TypeError(
+            `Failed to execute 'forEach' on '${name}': parameter 1 is not of type 'Function'.`
+          )
+        }
+        for (const { 0: key, 1: value } of makeIterator(this, 'key+value')) {
+          callbackfn.call(thisArg, value, key, this)
+        }
+      }
+    }
+  }
+
+  return Object.defineProperties(object.prototype, {
+    ...properties,
+    [Symbol.iterator]: {
+      writable: true,
+      enumerable: false,
+      configurable: true,
+      value: properties.entries.value
+    }
+  })
 }
 
 /**
@@ -1340,7 +1433,6 @@ module.exports = {
   isCancelled,
   createDeferredPromise,
   ReadableStreamFrom,
-  toUSVString,
   tryUpgradeRequestToAPotentiallyTrustworthyURL,
   clampAndCoarsenConnectionTimingInfo,
   coarsenedSharedCurrentTime,
@@ -1365,7 +1457,8 @@ module.exports = {
   sameOrigin,
   normalizeMethod,
   serializeJavascriptValueToJSONString,
-  makeIterator,
+  iteratorMixin,
+  createIterator,
   isValidHeaderName,
   isValidHeaderValue,
   isErrorLike,
diff --git a/lib/fetch/webidl.js b/lib/fetch/webidl.js
index d639b8b7668..a93a25505fc 100644
--- a/lib/fetch/webidl.js
+++ b/lib/fetch/webidl.js
@@ -1,7 +1,7 @@
 'use strict'
 
 const { types } = require('node:util')
-const { toUSVString } = require('./util')
+const { toUSVString } = require('../core/util')
 
 /** @type {import('../../types/webidl').Webidl} */
 const webidl = {}
diff --git a/test/fetch/headers.js b/test/fetch/headers.js
index b61d8b612d2..fcdf4b7a820 100644
--- a/test/fetch/headers.js
+++ b/test/fetch/headers.js
@@ -472,6 +472,21 @@ test('Headers as Iterable', async (t) => {
 
     deepStrictEqual([...headers], expected)
   })
+
+  await t.test('always use the same prototype Iterator', (t) => {
+    const HeadersIteratorNext = Function.call.bind(new Headers()[Symbol.iterator]().next)
+
+    const init = [
+      ['a', '1'],
+      ['b', '2']
+    ]
+
+    const headers = new Headers(init)
+    const iterator = headers[Symbol.iterator]()
+    assert.deepStrictEqual(HeadersIteratorNext(iterator), { value: init[0], done: false })
+    assert.deepStrictEqual(HeadersIteratorNext(iterator), { value: init[1], done: false })
+    assert.deepStrictEqual(HeadersIteratorNext(iterator), { value: undefined, done: true })
+  })
 })
 
 test('arg validation', () => {