diff --git a/rollup.config.js b/rollup.config.js
index ede9a34..697869a 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -36,7 +36,7 @@ const debugResolve = {
         return `${process.cwd()}/../yjs/src/index.js`
       }
       if (customModules.has(importee.split('/')[0])) {
-        return `${process.cwd()}/../${importee}/src/${importee}.cjs`
+        return `${process.cwd()}/../${importee}/src/${importee}.js`
       }
       if (customLibModules.has(importee.split('/')[0])) {
         return `${process.cwd()}/../${importee}`