diff --git a/README.md b/README.md
index c75cd226..37fe9c26 100644
--- a/README.md
+++ b/README.md
@@ -15,20 +15,33 @@ interface SomeInterface {
 combined with the JavaScript implementation class file
 
 ```js
-exports.implementation = class SomeInterfaceImpl {
+module.exports = class SomeInterfaceImpl {
   add(x, y) {
     return x + y;
   }
 };
 ```
 
+> Note: It's also possible to use ES2015 module default export syntax:
+>
+> ```js
+> export default class SomeInterfaceImpl {
+>   add(x, y) {
+>     return x + y;
+>   }
+> };
+> ```
+
 will generate a JavaScript wrapper class file roughly like this:
 
 ```js
 const conversions = require("webidl-conversions");
-const impl = require("./utils.js").implSymbol;
+const utils = require("./utils.js");
+const impl = utils.implSymbol;
 
-const Impl = require("./SomeInterface-impl.js").implementation;
+// utils.importStar is roughly equivalent to Babel's _interopRequireWildcard()
+// and TypeScript's __importStar() functions.
+const Impl = utils.importStar(require("./SomeInterface-impl.js")).default;
 
 class SomeInterface {
   constructor() {
diff --git a/lib/output/utils.js b/lib/output/utils.js
index dc1300a7..c1a4cba3 100644
--- a/lib/output/utils.js
+++ b/lib/output/utils.js
@@ -84,7 +84,9 @@ const importStarCache = new WeakMap();
  *
  * @template T
  * @param {T} obj
- * @return {T extends { default: any } ? T : { default: T } & { [K in keyof T]: T[K]; }}
+ * @return {T extends { default: any }
+ * ? T : T extends string | number | bigint | boolean | symbol | null | undefined
+ * ? { default: T } : { default: T } & { [K in keyof T]: T[K] }}
  */
 function importStar(obj) {
   if (obj && obj.__esModule) {