1 files changed, 4 insertions, 4 deletions

diff --git a/packages/shared/vite.config.js b/packages/shared/vite.config.js
index cbebb8a..05ec118 100644
--- a/packages/shared/vite.config.js
+++ b/packages/shared/vite.config.js
@@ -26,15 +26,15 @@ const config = {
     outDir: 'dist',
     lib: {
       entry: 'src/index.ts',
-      formats: ['cjs'],
+      formats: ['cjs', 'es'],
+      fileName: (format) => format === 'cjs' ? 'index.cjs' : `index.${format}.js`,
     },
     rollupOptions: {
       external: [
+        'mobx',
+        'mobx-state-tree',
         ...builtinModules,
       ],
-      output: {
-        entryFileNames: '[name].cjs',
-      },
     },
     emptyOutDir: false, // Do not remove `.d.ts` files.
     brotliSize: false,