diff --git a/packages/shared-internals/src/rewritten-package-cache.ts b/packages/shared-internals/src/rewritten-package-cache.ts
index cc50b0f9c..d2a4971e2 100644
--- a/packages/shared-internals/src/rewritten-package-cache.ts
+++ b/packages/shared-internals/src/rewritten-package-cache.ts
@@ -1,6 +1,6 @@
 import PackageCache from './package-cache';
 import Package from './package';
-import { ensureDirSync, existsSync, readJSONSync, realpathSync } from 'fs-extra';
+import { existsSync, readJSONSync, realpathSync } from 'fs-extra';
 import { resolve } from 'path';
 import { getOrCreate } from './get-or-create';
 import { locateEmbroiderWorkingDir } from './working-dir';
@@ -133,8 +133,8 @@ export class RewrittenPackageCache implements PublicAPI<PackageCache> {
   }
 
   private loadIndex(): RewrittenPackageCache['index'] {
-    let addonsDir = resolve(locateEmbroiderWorkingDir(this.appRoot), 'rewritten-packages');
-    let indexFile = resolve(addonsDir, 'index.json');
+    let workingDir = locateEmbroiderWorkingDir(this.appRoot);
+    let indexFile = resolve(workingDir, 'rewritten-packages', 'index.json');
     if (!existsSync(indexFile)) {
       return {
         oldToNew: new Map(),
@@ -143,25 +143,16 @@ export class RewrittenPackageCache implements PublicAPI<PackageCache> {
       };
     }
 
-    // this directory is a bit special because RewrittenPackageCache needs to
-    // exist before this dir has been produced. But the dir appears preemptively
-    // in our index, and we don't want that to blow up during the realpath
-    // below.
-    ensureDirSync(resolve(addonsDir, '..', 'rewritten-app'));
+    workingDir = realpathSync(workingDir);
+    let addonsDir = resolve(workingDir, 'rewritten-packages');
 
     let { packages, extraResolutions } = readJSONSync(indexFile) as RewrittenPackageIndex;
     return {
       oldToNew: new Map(
-        Object.entries(packages).map(([oldRoot, newRoot]) => [
-          realpathSync(resolve(addonsDir, oldRoot)),
-          realpathSync(resolve(addonsDir, newRoot)),
-        ])
+        Object.entries(packages).map(([oldRoot, newRoot]) => [resolve(addonsDir, oldRoot), resolve(addonsDir, newRoot)])
       ),
       newToOld: new Map(
-        Object.entries(packages).map(([oldRoot, newRoot]) => [
-          realpathSync(resolve(addonsDir, newRoot)),
-          realpathSync(resolve(addonsDir, oldRoot)),
-        ])
+        Object.entries(packages).map(([oldRoot, newRoot]) => [resolve(addonsDir, newRoot), resolve(addonsDir, oldRoot)])
       ),
       extraResolutions: new Map(
         Object.entries(extraResolutions).map(([fromRoot, toRoots]) => [