diff --git a/src/vs/base/node/event.ts b/src/vs/base/node/event.ts
index 5ba3b481692..f30a05111a4 100644
--- a/src/vs/base/node/event.ts
+++ b/src/vs/base/node/event.ts
@@ -8,7 +8,7 @@
 import Event, { Emitter }  from 'vs/base/common/event';
 import { EventEmitter } from 'events';
 
-export function fromEventEmitter<T>(emitter: EventEmitter, eventName: string, map: (...args: any[]) => T = ([arg]) => arg): Event<T> {
+export function fromEventEmitter<T>(emitter: EventEmitter, eventName: string, map: (...args: any[]) => T): Event<T> {
 	const fn = (...args) => result.fire(map(...args));
 	const onFirstListenerAdd = () => emitter.on(eventName, fn);
 	const onLastListenerRemove = () => emitter.removeListener(eventName, fn);