diff --git a/CHANGELOG.md b/CHANGELOG.md
index 537e3d19..7634e8f8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@
 
 - "You know what they say ‘Fool me once, strike one, but fool me twice… strike three.’" — Michael Scott
 
+## 3.3.1
+
+- fix(webpack5): All `esm` files must have `.mjs` postfix (#721)
+
 ## 3.3.0
 
 - feat(webpack): Add `@sentry/webpack-plugin/webpack5` export for webpack 5.1+ and compatible environments (#715)
diff --git a/packages/webpack-plugin/rollup.config.js b/packages/webpack-plugin/rollup.config.js
index 3f0be962..ea1dc3b6 100644
--- a/packages/webpack-plugin/rollup.config.js
+++ b/packages/webpack-plugin/rollup.config.js
@@ -38,12 +38,15 @@ export default {
       exports: "named",
       sourcemap: true,
       entryFileNames: "[name].mjs",
+      chunkFileNames: "[name].mjs",
     },
     {
       dir: "./dist/cjs",
       format: "cjs",
       exports: "named",
       sourcemap: true,
+      entryFileNames: "[name].js",
+      chunkFileNames: "[name].js",
     },
   ],
 };