diff --git a/packages/evalite/package.json b/packages/evalite/package.json
index b5ff29d..873a2ae 100644
--- a/packages/evalite/package.json
+++ b/packages/evalite/package.json
@@ -10,7 +10,7 @@
   ],
   "scripts": {
     "dev": "tsc -w",
-    "build": "tsc"
+    "build": "tsc && chmod +x ./dist/bin.js"
   },
   "exports": {
     ".": "./dist/index.js",
diff --git a/packages/example/src/cache-model.ts b/packages/example/src/cache-model.ts
index 2b4ac1c..0709986 100644
--- a/packages/example/src/cache-model.ts
+++ b/packages/example/src/cache-model.ts
@@ -18,13 +18,14 @@ const createResultFromCachedObject = (
   return obj as any;
 };
 
-export const cacheModel = (
-  model: LanguageModelV1,
-  storage: {
-    get: (key: string) => Promise<object>;
-    set: (key: string, value: string) => Promise<void>;
-  }
-) => {
+export type StorageValue = string | number | null | object;
+
+export type CacheStore = {
+  get: (key: string) => Promise<StorageValue>;
+  set: (key: string, value: StorageValue) => Promise<void>;
+};
+
+export const cacheModel = (model: LanguageModelV1, storage: CacheStore) => {
   return experimental_wrapLanguageModel({
     model,
     middleware: {