diff --git a/lib/removeWorkspaceDuplicates.js b/lib/removeWorkspaceDuplicates.js
new file mode 100644
index 0000000..dee5850
--- /dev/null
+++ b/lib/removeWorkspaceDuplicates.js
@@ -0,0 +1,54 @@
+import fs from 'fs'
+import path from 'path'
+
+function globToRegExp (glob) {
+  let rex = glob.replace(/\*\*/g, '.*')
+  rex = rex.replace(/\*/g, '[^/]*')
+  rex = rex.replace(/\\\\/g, '\/')
+  rex = rex.replace(/\./g, '\\.')
+  rex = rex.replace(/\//g, '\\/')
+  rex = `^${rex}$`
+  return new RegExp(rex, 'gm')
+}
+
+function unix(path) {
+  return path.replace(/\\/g,'/')
+}
+
+async function getAllSubDirs (dir, depth = Number.MAX_SAFE_INTEGER) {
+  async function collectPaths(dir, root = dir, level = 0) {
+    const subs = await fs.promises.readdir(dir)
+    const paths = []
+    for (let sub of subs) {
+      sub = path.resolve(dir, sub)
+      const relativeSub = unix(sub).replace(root + '/', '')
+      const stat = await fs.promises.stat(sub)
+      if (!stat || !stat.isDirectory()) continue
+      paths.push(relativeSub)
+      if (depth === level) continue
+      paths.push(...await collectPaths(sub, root, level+1))
+    }
+    return paths
+  }
+  const root = unix(path.resolve(process.cwd(), dir))
+  return collectPaths(root)
+}
+
+async function globs (glob, { cwd = process.cwd(), depth } = {}) {
+  const subDirs = await getAllSubDirs(cwd, depth)
+  const rex = globToRegExp(glob)
+  return subDirs.filter(subDir => rex.test(subDir))
+}
+
+async function cleanUpSubDependencies() {
+  const localModuleNames = await globs('*', { cwd: './local_adapt_modules', depth: 1 })
+  const subModules = await globs('adapt-authoring*/node_modules/adapt-authoring*', { cwd: 'node_modules/', depth: 3 })
+  for (let subModule of subModules) {
+    const subModuleName = subModule.split('/').pop()
+    if (!localModuleNames.includes(subModuleName)) continue
+    console.warn(`Removing erroneous sub dependency ${subModule}`)
+    await fs.promises.rm(`node_modules/${subModule}`, { recursive:true })
+  }
+}
+
+cleanUpSubDependencies()
diff --git a/package.json b/package.json
index d79731e..198b0ec 100644
--- a/package.json
+++ b/package.json
@@ -9,7 +9,8 @@
   "scripts": {
     "debug": "node --inspect --preserve-symlinks ./bin/start",
     "dev": "node ./bin/dev",
-    "start": "node ./bin/start"
+    "start": "node ./bin/start",
+    "postinstall": "node ./lib/removeWorkspaceDuplicates.js"
   },
   "dependencies": {
     "adapt-authoring-adaptframework": "github:adapt-security/adapt-authoring-adaptframework",