diff --git a/CHANGELOG.md b/CHANGELOG.md
index 448154894..b89f48be3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+### Fixed
+- [JavaScript] The `ParameterType` constructor's `transform`, `useForSnippets` and `preferForRegexpMatch` should be optional. ([#178](https://github.com/cucumber/cucumber-expressions/pull/178))
 
 ## [16.0.0] - 2022-06-12
 ### Changed
diff --git a/javascript/src/ParameterType.ts b/javascript/src/ParameterType.ts
index 3493fe262..62e4715e2 100644
--- a/javascript/src/ParameterType.ts
+++ b/javascript/src/ParameterType.ts
@@ -54,9 +54,9 @@ export default class ParameterType<T> {
     public readonly name: string | undefined,
     regexps: RegExps,
     public readonly type: Constructor<T> | Factory<T> | null,
-    transform: (...match: string[]) => T | PromiseLike<T>,
-    public readonly useForSnippets: boolean,
-    public readonly preferForRegexpMatch: boolean
+    transform?: (...match: string[]) => T | PromiseLike<T>,
+    public readonly useForSnippets?: boolean,
+    public readonly preferForRegexpMatch?: boolean
   ) {
     if (transform === undefined) {
       transform = (s) => s as unknown as T