From d4e106f4bd4f02ad33ddd54cec9341783740aad0 Mon Sep 17 00:00:00 2001
From: Trent Mick <trentm@gmail.com>
Date: Mon, 26 Jan 2026 12:22:23 -0800
Subject: [PATCH 1/2] fix: properly hook builtin modules that require the
 'node:' prefix

---
 index.js                                | 13 ++++++++++---
 test/hook/v18.15-node-prefixed-only.mjs | 12 ++++++++++++
 2 files changed, 22 insertions(+), 3 deletions(-)
 create mode 100644 test/hook/v18.15-node-prefixed-only.mjs

diff --git a/index.js b/index.js
index 38a7d0d..a9e0915 100644
--- a/index.js
+++ b/index.js
@@ -6,6 +6,7 @@ const path = require('path')
 const parse = require('module-details-from-path')
 const { fileURLToPath } = require('url')
 const { MessageChannel } = require('worker_threads')
+const { isBuiltin } = require('module')
 
 const {
   importHooks,
@@ -124,11 +125,17 @@ function Hook (modules, options, hookFn) {
 
   this._iitmHook = (name, namespace, specifier) => {
     const filename = name
-    const isBuiltin = name.startsWith('node:')
+    const isNodeUrl = name.startsWith('node:')
     let baseDir
 
-    if (isBuiltin) {
-      name = name.replace(/^node:/, '')
+    if (isNodeUrl) {
+      // Normalize builtin module name to *not* have 'node:' prefix, unless
+      // required, as it is for 'node:test' and some others.  `module.isBuiltin`
+      // is available in all Node.js versions that have node:-only modules.
+      const unprefixed = name.slice(5)
+      if (typeof isBuiltin !== 'function' || isBuiltin(unprefixed)) {
+        name = unprefixed
+      }
     } else {
       if (name.startsWith('file://')) {
         const stackTraceLimit = Error.stackTraceLimit
diff --git a/test/hook/v18.15-node-prefixed-only.mjs b/test/hook/v18.15-node-prefixed-only.mjs
new file mode 100644
index 0000000..e501d1e
--- /dev/null
+++ b/test/hook/v18.15-node-prefixed-only.mjs
@@ -0,0 +1,12 @@
+// Test that a builtin module that must use 'node:' prefix works.
+import { strictEqual } from 'assert'
+import Hook from '../../index.js'
+
+Hook(['node:test'], (exports, name) => {
+  if (name === 'node:test') {
+    exports.skip = 'iitm was here'
+  }
+})
+
+const { skip } = await import('node:test')
+strictEqual(skip, 'iitm was here')

From d5eb78966009392fef09d6a068b6dd55306cdb5c Mon Sep 17 00:00:00 2001
From: Trent Mick <trentm@gmail.com>
Date: Mon, 26 Jan 2026 16:22:55 -0800
Subject: [PATCH 2/2] provide fallback for isBuiltin to avoid typeof check
 everytime

---
 index.js | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index a9e0915..0725304 100644
--- a/index.js
+++ b/index.js
@@ -6,7 +6,11 @@ const path = require('path')
 const parse = require('module-details-from-path')
 const { fileURLToPath } = require('url')
 const { MessageChannel } = require('worker_threads')
-const { isBuiltin } = require('module')
+
+let { isBuiltin } = require('module')
+if (!isBuiltin) {
+  isBuiltin = () => true
+}
 
 const {
   importHooks,
@@ -133,7 +137,7 @@ function Hook (modules, options, hookFn) {
       // required, as it is for 'node:test' and some others.  `module.isBuiltin`
       // is available in all Node.js versions that have node:-only modules.
       const unprefixed = name.slice(5)
-      if (typeof isBuiltin !== 'function' || isBuiltin(unprefixed)) {
+      if (isBuiltin(unprefixed)) {
         name = unprefixed
       }
     } else {