diff --git a/lib/utils/completion/installed-shallow.js b/lib/utils/completion/installed-shallow.js
index 3e4342a4aaa8a..d59318fe78541 100644
--- a/lib/utils/completion/installed-shallow.js
+++ b/lib/utils/completion/installed-shallow.js
@@ -1,9 +1,10 @@
 const { readdirScoped } = require('@npmcli/fs')
-const { posix } = require('path')
 
 const installedShallow = async (npm, opts) => {
-  const names = global => readdirScoped(global ? npm.globalDir : npm.localDir)
-    .then(list => list.map(i => posix.join(i)))
+  const names = async global => {
+    const paths = await readdirScoped(global ? npm.globalDir : npm.localDir)
+    return paths.map(p => p.replace(/\\/g, '/'))
+  }
   const { conf: { argv: { remain } } } = opts
   if (remain.length > 3) {
     return null
diff --git a/workspaces/arborist/lib/arborist/build-ideal-tree.js b/workspaces/arborist/lib/arborist/build-ideal-tree.js
index 3dc53d742f6ff..d64bdd7e496ae 100644
--- a/workspaces/arborist/lib/arborist/build-ideal-tree.js
+++ b/workspaces/arborist/lib/arborist/build-ideal-tree.js
@@ -6,7 +6,7 @@ const pacote = require('pacote')
 const cacache = require('cacache')
 const promiseCallLimit = require('promise-call-limit')
 const realpath = require('../../lib/realpath.js')
-const { resolve, dirname, posix } = require('path')
+const { resolve, dirname } = require('path')
 const treeCheck = require('../tree-check.js')
 const { readdirScoped } = require('@npmcli/fs')
 const { lstat, readlink } = require('fs/promises')
@@ -446,8 +446,8 @@ module.exports = cls => class IdealTreeBuilder extends cls {
     const globalExplicitUpdateNames = []
     if (this[_global] && (this[_updateAll] || this[_updateNames].length)) {
       const nm = resolve(this.path, 'node_modules')
-      for (const namePath of await readdirScoped(nm).catch(() => [])) {
-        const name = posix.join(namePath)
+      const paths = await readdirScoped(nm).catch(() => [])
+      for (const name of paths.map((p) => p.replace(/\\/g, '/'))) {
         tree.package.dependencies = tree.package.dependencies || {}
         const updateName = this[_updateNames].includes(name)
         if (this[_updateAll] || updateName) {
diff --git a/workspaces/arborist/lib/arborist/load-actual.js b/workspaces/arborist/lib/arborist/load-actual.js
index 3f1eeebf56b31..6c3f917c6ac9d 100644
--- a/workspaces/arborist/lib/arborist/load-actual.js
+++ b/workspaces/arborist/lib/arborist/load-actual.js
@@ -1,6 +1,6 @@
 // mix-in implementing the loadActual method
 
-const { relative, dirname, resolve, join, normalize, posix } = require('path')
+const { relative, dirname, resolve, join, normalize } = require('path')
 
 const rpj = require('read-package-json-fast')
 const { readdirScoped } = require('@npmcli/fs')
@@ -361,7 +361,7 @@ module.exports = cls => class ActualLoader extends cls {
   async [_loadFSChildren] (node) {
     const nm = resolve(node.realpath, 'node_modules')
     try {
-      const kids = await readdirScoped(nm).then(list => list.map(i => posix.join(i)))
+      const kids = await readdirScoped(nm).then(paths => paths.map(p => p.replace(/\\/g, '/')))
       return Promise.all(
         // ignore . dirs and retired scoped package folders
         kids.filter(kid => !/^(@[^/]+\/)?\./.test(kid))
@@ -411,7 +411,7 @@ module.exports = cls => class ActualLoader extends cls {
           }
 
           const entries = nmContents.get(p) || await readdirScoped(p + '/node_modules')
-            .catch(() => []).then(list => list.map(i => posix.join(i)))
+            .catch(() => []).then(paths => paths.map(p => p.replace(/\\/g, '/')))
           nmContents.set(p, entries)
           if (!entries.includes(name)) {
             continue