diff --git a/testcases/test-env/test-tsc/js-commonjs.js b/testcases/test-env/test-tsc/js-commonjs.ts
similarity index 100%
rename from testcases/test-env/test-tsc/js-commonjs.js
rename to testcases/test-env/test-tsc/js-commonjs.ts
diff --git a/testcases/test-env/test-tsc/js-module.js b/testcases/test-env/test-tsc/js-module.ts
similarity index 100%
rename from testcases/test-env/test-tsc/js-module.js
rename to testcases/test-env/test-tsc/js-module.ts
diff --git a/testcases/test-env/test-tsc/prepare.cjs b/testcases/test-env/test-tsc/prepare.cjs
index dc5fac811..de4cf0aa8 100644
--- a/testcases/test-env/test-tsc/prepare.cjs
+++ b/testcases/test-env/test-tsc/prepare.cjs
@@ -16,4 +16,4 @@ replace("tsconfig.json", "${TS_MODULE}", process.argv[3]);
 replace("package.json", "${PKG_TYPE}", process.argv[4]);
 
 // JavaScript
-fs.writeFileSync("index.js", fs.readFileSync("js-" + process.argv[4] + ".js"));
+fs.writeFileSync("index.ts", fs.readFileSync("js-" + process.argv[4] + ".ts"));