diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index a4fce2940..fe3392479 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -52,6 +52,7 @@ All definitions files include a header with the author and editors, so at some p
 * [bunyan-logentries](https://github.com/nemtsov/node-bunyan-logentries) (by [Aymeric Beaumet](http://aymericbeaumet.me))
 * [CasperJS](http://casperjs.org) (by [Jed Mao](https://github.com/jedmao))
 * [CanvasJS](http://canvasjs.com) (by [Mark Overholt](https://github.com/mover5))
+* [checksum](https://github.com/dshaw/checksum) (by [Rogier Schouten](https://github.com/rogierschouten))
 * [Cheerio](https://github.com/MatthewMueller/cheerio) (by [Bret Little](https://github.com/blittle))
 * [Chosen](http://harvesthq.github.com/chosen/) (by [Boris Yankov](https://github.com/borisyankov))
 * [Chroma.js](https://github.com/gka/chroma.js) (by [Sebastian Brückner](https://github.com/invliD))
diff --git a/checksum/checksum-tests.ts b/checksum/checksum-tests.ts
new file mode 100644
index 000000000..de9faaa98
--- /dev/null
+++ b/checksum/checksum-tests.ts
@@ -0,0 +1,14 @@
+/// <reference path="checksum.d.ts" />
+
+import checksum = require("checksum");
+
+var s: string = checksum("abcd");
+var t: string = checksum("abcd", { algorithm: 'sha1' });
+
+checksum.file("myfile.txt", (error: Error, hash: string): void => {
+	// do nothing
+});
+
+checksum.file("myfile.txt", { algorithm: 'sha1' }, (error: Error, hash: string): void => {
+	// do nothing
+});
diff --git a/checksum/checksum.d.ts b/checksum/checksum.d.ts
new file mode 100644
index 000000000..63f24224e
--- /dev/null
+++ b/checksum/checksum.d.ts
@@ -0,0 +1,44 @@
+// Type definitions for checksum 0.1.1
+// Project: https://github.com/dshaw/checksum
+// Definitions by: Rogier Schouten <https://github.com/rogierschouten>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+declare module "checksum" {
+	
+	module checksum {
+		/**
+		 * Options object for all functions
+		 */
+		interface ChecksumOptions {
+			/**
+			 * Algorithm to use, default 'sha1'
+			 * Can be 'sha1' or 'md5'  (see module 'crypto').
+			 */
+			algorithm?: string;
+		}
+		
+		/**
+		 * Generate the checksum for a file on disk
+		 * @param filename	The file name
+		 * @param callback	Callback which is called with the result or an error 
+		 */
+		function file(filename: string, callback: (error: Error, hash: string) => void): void;
+		/**
+		 * Generate the checksum for a file on disk
+		 * @param filename	The file name
+		 * @param options	Options object to indicate hash algo
+		 * @param callback	Callback which is called with the result or an error 
+		 */
+		function file(filename: string, options: ChecksumOptions, callback: (error: Error, hash: string) => void): void;
+	}
+	
+	/**
+	 * Generates a checksum for the given value
+	 * @param value	Any value
+	 * @param options	Allows to set the algorithm
+	 * @returns	Checksum
+	 */
+	function checksum(value: any, options?: checksum.ChecksumOptions): string;
+	
+	export = checksum;
+}