diff --git a/packages/test-runner-mocha/package.json b/packages/test-runner-mocha/package.json
index 7bfc316e9..2c1e98272 100644
--- a/packages/test-runner-mocha/package.json
+++ b/packages/test-runner-mocha/package.json
@@ -19,7 +19,7 @@
   },
   "scripts": {
     "build": "tsc",
-    "build:production": "rimraf dist && rollup -c rollup.config.js",
+    "build:production": "rimraf dist && rollup -c ./rollup.config.mjs",
     "test": "mocha test/**/*.test.js",
     "test:watch": "mocha test/**/*.test.js --watch --watch-files src,test"
   },
diff --git a/packages/test-runner-mocha/rollup.config.js b/packages/test-runner-mocha/rollup.config.mjs
similarity index 96%
rename from packages/test-runner-mocha/rollup.config.js
rename to packages/test-runner-mocha/rollup.config.mjs
index 8db9c72c8..630573815 100644
--- a/packages/test-runner-mocha/rollup.config.js
+++ b/packages/test-runner-mocha/rollup.config.mjs
@@ -1,5 +1,5 @@
 import deepmerge from 'deepmerge';
-import createConfig from '../../rollup.browser.config';
+import createConfig from '../../rollup.browser.config.mjs';
 
 const REGEXP_DTS_MOCHA = /'..\/..\/..\/node_modules\/mocha\/mocha.js'/g;
 const REGEXP_DTS_CORE = /'..\/..\/test-runner-core\/browser\/session.js'/g;
diff --git a/rollup.browser.config.js b/rollup.browser.config.mjs
similarity index 100%
rename from rollup.browser.config.js
rename to rollup.browser.config.mjs