diff --git a/README.md b/README.md
index d5434fe8..9b3bcc7c 100644
--- a/README.md
+++ b/README.md
@@ -201,18 +201,22 @@ QUnit.done(async () => {
 });
 ```
 
-Under the hood, `ember-cli-code-coverage` creates a mapping of app and addon namespaces to their actual on disk locations. While in general this
-works correctly in the rare execption you can customize this via:
+Under the hood, `ember-cli-code-coverage` attempts to "de-namespacify" paths into their real on disk location inside of
+`project.root` (ie give a namespaced path like lib/inrepo/components/foo.js would live in lib/inrepo/addon/components/foo.js). It makes
+some assumptions (where files live in in-repo addons vs app code for example) and sometimes those assumptions might not hold. Passing a
+function `modifyAssetLocation` will allow you to override where a file actually lives inside of your project. The returned string should
+be relative to your project root.
 
 ```js
 const app = new EmberApp(defaults, {
   'ember-cli-code-coverage': {
-    namespaceOverride(item, namespace) {
-      if (item.name === 'common') {
-        namespace.set(item.name, 'some-full-path/addon');
-        namespace.set(path.join(item.name, 'test-support'), 'some-full-path/addon-test-support');
-        return true;
+    modifyAssetLocation(root, relativePath) {
+      // here is an example of saying that `component/foo.js` actually
+      // lives in `lib/common/app/foo.js` on disk.
+      if (fs.existsSync(path.join(root, 'lib/inrepo/app', relativePath))) {
+        return path.join('lib/common/app', relativePath);
       }
+
       return false;
     },
   },
diff --git a/packages/ember-cli-code-coverage/index.js b/packages/ember-cli-code-coverage/index.js
index 3cb4a6e7..35918811 100644
--- a/packages/ember-cli-code-coverage/index.js
+++ b/packages/ember-cli-code-coverage/index.js
@@ -74,24 +74,19 @@ module.exports = {
   included(app) {
     this._super.included.apply(this, arguments);
     let config = app.options[this.name] || {};
-    this.namespaceOverride = config && config.namespaceOverride;
+    this.modifyAssetLocation = config && config.modifyAssetLocation;
   },
 
-  buildNamespaceMappings(namespaceOverride) {
+  buildNamespaceMappings() {
     let rootNamespaceMappings = new Map();
-    function recurse(item, namespaceOverride) {
-      let override = false;
-      if (namespaceOverride) {
-        override = namespaceOverride(item, rootNamespaceMappings);
-      }
-
-      if (item.isEmberCLIProject && item.isEmberCLIProject() && !override) {
+    function recurse(item) {
+      if (item.isEmberCLIProject && item.isEmberCLIProject()) {
         let projectConfig = item.config(process.env.EMBER_ENV);
         rootNamespaceMappings.set(
           projectConfig.modulePrefix,
           path.join(item.root, 'app')
         );
-      } else if (item.treePaths && !override) {
+      } else if (item.treePaths) {
         let addonPath = path.join(item.root, item.treePaths.addon);
         let addonTestSupportPath = path.join(
           item.root,
@@ -103,10 +98,10 @@ module.exports = {
           addonTestSupportPath
         );
       }
-      item.addons.forEach((i) => recurse(i, namespaceOverride));
+      item.addons.forEach((i) => recurse(i));
     }
 
-    recurse(this.project, namespaceOverride);
+    recurse(this.project);
 
     // this adds a "default" lookup to the namespace in the event that there is no
     // namespace. this comes up under embroider depending on the app structure of
@@ -130,7 +125,8 @@ module.exports = {
       configPath: this.project.configPath(),
       root: this.project.root,
       fileLookup: this.fileLookup,
-      namespaceMappings: this.buildNamespaceMappings(this.namespaceOverride),
+      namespaceMappings: this.buildNamespaceMappings(),
+      modifyAssetLocation: this.modifyAssetLocation,
     });
   },
 
@@ -139,7 +135,8 @@ module.exports = {
       configPath: this.project.configPath(),
       root: this.project.root,
       fileLookup: this.fileLookup,
-      namespaceMappings: this.buildNamespaceMappings(this.namespaceOverride),
+      namespaceMappings: this.buildNamespaceMappings(),
+      modifyAssetLocation: this.modifyAssetLocation,
     };
     // if we're running `ember test --server` use the `serverMiddleware`.
     if (process.argv.includes('--server') || process.argv.includes('-s')) {
diff --git a/packages/ember-cli-code-coverage/lib/attach-middleware.js b/packages/ember-cli-code-coverage/lib/attach-middleware.js
index a45401f2..39b0887c 100644
--- a/packages/ember-cli-code-coverage/lib/attach-middleware.js
+++ b/packages/ember-cli-code-coverage/lib/attach-middleware.js
@@ -62,7 +62,12 @@ function normalizeRelativePath(root, filepath) {
  * where as in Classic it will be the "actual" app like: `/Users/x/y/z/ember-test-app/ember-test-app/components/foo.js`
  * both of these absolute paths should be converted into `app/components/foo.js`
  */
-function adjustCoverageKey(root, filepath, namespaceMappings) {
+function adjustCoverageKey(
+  root,
+  filepath,
+  namespaceMappings,
+  modifyAssetLocation
+) {
   let relativePath = path.relative(root, filepath);
   let embroiderTmpPathRegex = /embroider\/.{6}/gm;
 
@@ -81,6 +86,19 @@ function adjustCoverageKey(root, filepath, namespaceMappings) {
     pathWithoutNamespace = pathWithoutNamespace.slice(1);
   }
 
+  if (modifyAssetLocation) {
+    let customPath = modifyAssetLocation(
+      root,
+      relativePath,
+      filepath,
+      namespaceMappings
+    );
+
+    if (customPath) {
+      return customPath;
+    }
+  }
+
   if (namespaceMappings.has(namespaceKey)) {
     return path.join(
       ...[namespaceMappings.get(namespaceKey), ...pathWithoutNamespace]
@@ -94,12 +112,13 @@ function adjustCoverageKey(root, filepath, namespaceMappings) {
 }
 
 function adjustCoverage(coverage, options) {
-  let { root, namespaceMappings } = options;
+  let { root, namespaceMappings, modifyAssetLocation } = options;
   const adjustedCoverage = Object.keys(coverage).reduce((memo, filePath) => {
     let relativeToProjectRoot = adjustCoverageKey(
       root,
       filePath,
-      namespaceMappings
+      namespaceMappings,
+      modifyAssetLocation
     );
     coverage[filePath].path = path.relative(root, relativeToProjectRoot);
     memo[path.relative(root, relativeToProjectRoot)] = coverage[filePath];