diff --git a/node/node-tests.ts b/node/node-tests.ts
index 397a9dfa4..f82fb9530 100644
--- a/node/node-tests.ts
+++ b/node/node-tests.ts
@@ -6,6 +6,7 @@ import events = require("events");
 import zlib = require("zlib");
 import url = require('url');
 import util = require("util");
+import crypto = require("crypto");
 
 assert(1 + 1 - 2 === 0, "The universe isn't how it should.");
 
@@ -80,3 +81,10 @@ function stream_readable_pipe_test() {
     var w = fs.createWriteStream('file.txt.gz');
     r.pipe(z).pipe(w);
 }
+
+
+////////////////////////////////////////////////////
+/// Crypto tests : http://nodejs.org/api/crypto.html
+////////////////////////////////////////////////////
+
+var hmacResult: string = crypto.createHmac('md5', 'hello').update('world').digest('hex');
diff --git a/node/node.d.ts b/node/node.d.ts
index b8cc7d933..7e9474087 100644
--- a/node/node.d.ts
+++ b/node/node.d.ts
@@ -1021,8 +1021,8 @@ declare module "crypto" {
         digest(encoding?: string): string;
     }
     interface Hmac {
-        update(data: any): void;
-        digest(encoding?: string): void;
+        update(data: any, input_encoding?: string): Hmac;
+        digest(encoding?: string): string;
     }
     export function createCipher(algorithm: string, password: any): Cipher;
     export function createCipheriv(algorithm: string, key: any, iv: any): Cipher;