diff --git a/package.json b/package.json
index c8fa6e6..5d64749 100644
--- a/package.json
+++ b/package.json
@@ -15,8 +15,10 @@
   "types": "./dist/lib/index.d.ts",
   "exports": {
     ".": {
-      "import": "./dist/client.mjs",
-      "require": "./dist/client.umd.js"
+      "types": "./dist/lib/index.d.ts",
+      "import": "./dist/client.js",
+      "require": "./dist/client.umd.cjs",
+      "default": "./dist/client.js"
     }
   },
   "scripts": {
diff --git a/vite.config.ts b/vite.config.ts
index bf108e4..93a5091 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -6,6 +6,10 @@ export default defineConfig({
     lib: {
       entry: './lib/index',
       name: 'client',
+      // Pinned explicitly: the defaults are derived from `type` and the Vite version, so an
+      // upgrade can silently rename the output and desync it from the `exports` map in package.json.
+      formats: ['es', 'umd'],
+      fileName: (format) => (format === 'es' ? 'client.js' : 'client.umd.cjs'),
     },
   },
   plugins: [dts()],