diff --git a/through2/through2-tests.ts b/through2/through2-tests.ts
index 6ea9a52d5f..e6f97fb712 100644
--- a/through2/through2-tests.ts
+++ b/through2/through2-tests.ts
@@ -22,6 +22,12 @@ rws = through2(function (entry: any, enc: string, callback: () => void) {
 
 });
 
+rws = through2(function (entry: any, enc: string, callback: (error: any, data?: any) => void) {
+	callback(null, 'foo');
+}, (flushCallback: () => void) => {
+	flushCallback();
+});
+
 rws = through2(function (entry: any, enc: string, callback: () => void) {
 	this.push('foo');
 	callback();
@@ -42,3 +48,8 @@ rws = through2.obj(function (entry: any, enc: string, callback: () => void) {
 	callback();
 });
 
+rws = through2.obj(function (entry: any, enc: string, callback: (err: any) => void) {
+	callback('Oups!');
+}, (flashCallback) => {
+	flashCallback();
+});
diff --git a/through2/through2.d.ts b/through2/through2.d.ts
index 7481fa910f..32e566e72e 100644
--- a/through2/through2.d.ts
+++ b/through2/through2.d.ts
@@ -1,6 +1,6 @@
-// Type definitions for through2 v 0.4.2
+// Type definitions for through2 v 2.0.0
 // Project: https://github.com/rvagg/through2
-// Definitions by: Bart van der Schoor <https://github.com/Bartvds>, jedmao <https://github.com/jedmao>
+// Definitions by: Bart van der Schoor <https://github.com/Bartvds>, jedmao <https://github.com/jedmao>, Georgios Valotasios <https://github.com/valotas>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
 
 /// <reference path="../node/node.d.ts" />
@@ -8,14 +8,18 @@
 declare module 'through2' {
 
 	import stream = require('stream');
+	
+	type TransfofmCallback = (err?: any, data?: any) => void;
+	type TransformFunction = (chunk: any, enc: string, callback: TransfofmCallback) => void;
+	type FlashCallback = (flushCallback: () => void) => void;
 
-	function through2(transform?: (chunk: any, enc: string, callback: () => void) => void, flush?: () => void): NodeJS.ReadWriteStream;
+	function through2(transform?: TransformFunction, flush?: FlashCallback): NodeJS.ReadWriteStream;
 
-	function through2(opts?: stream.DuplexOptions, transform?: (chunk: any, enc: string, callback: () => void) => void, flush?: () => void): NodeJS.ReadWriteStream;
+	function through2(opts?: stream.DuplexOptions, transform?: TransformFunction, flush?: FlashCallback): NodeJS.ReadWriteStream;
 
 	module through2 {
 
-		export function obj(transform?: (chunk: any, enc: string, callback: () => void) => void, flush?: () => void): NodeJS.ReadWriteStream;
+		export function obj(transform?: TransformFunction, flush?: FlashCallback): NodeJS.ReadWriteStream;
 
 		export function push(data: any): void;