diff --git a/README.md b/README.md
index 937836878..6ee45b205 100644
--- a/README.md
+++ b/README.md
@@ -754,7 +754,7 @@ The first argument can be either a `url` or an `options` object. The only requir
 - `auth` - A hash containing values `user` || `username`, `pass` || `password`, and `sendImmediately` (optional).  See documentation above.
 - `oauth` - Options for OAuth HMAC-SHA1 signing. See documentation above.
 - `hawk` - Options for [Hawk signing](https://github.com/hueniverse/hawk). The `credentials` key must contain the necessary signing info, [see hawk docs for details](https://github.com/hueniverse/hawk#usage-example).
-- `aws` - `object` containing AWS signing information. Should have the properties `key`, `secret`. Also requires the property `bucket`, unless you’re specifying your `bucket` as part of the path, or the request doesn’t use a bucket (i.e. GET Services). If you want to use AWS sign version 4 use the parameter `sign_version` with value `4` otherwise the default is version 2.
+- `aws` - `object` containing AWS signing information. Should have the properties `key`, `secret`. Also requires the property `bucket`, unless you’re specifying your `bucket` as part of the path, or the request doesn’t use a bucket (i.e. GET Services). If you want to use AWS sign version 4 use the parameter `sign_version` with value `4` otherwise the default is version 2. **Note:** you need to `npm install aws4` first.
 - `httpSignature` - Options for the [HTTP Signature Scheme](https://github.com/joyent/node-http-signature/blob/master/http_signing.md) using [Joyent's library](https://github.com/joyent/node-http-signature). The `keyId` and `key` properties must be specified. See the docs for other options.
 
 ---
diff --git a/package.json b/package.json
index 7aefa7702..aeffc76ed 100644
--- a/package.json
+++ b/package.json
@@ -23,7 +23,6 @@
   "main": "index.js",
   "dependencies": {
     "aws-sign2": "~0.6.0",
-    "aws4": "^1.2.1",
     "bl": "~1.0.0",
     "caseless": "~0.11.0",
     "combined-stream": "~1.0.5",
@@ -52,6 +51,7 @@
     "lint": "eslint lib/ *.js tests/ && echo Lint passed."
   },
   "devDependencies": {
+    "aws4": "^1.2.1",
     "bluebird": "^3.0.2",
     "browserify": "^13.0.0",
     "browserify-istanbul": "^0.1.5",
diff --git a/request.js b/request.js
index 8dc900569..e4a181237 100644
--- a/request.js
+++ b/request.js
@@ -9,7 +9,6 @@ var http = require('http')
   , bl = require('bl')
   , hawk = require('hawk')
   , aws2 = require('aws-sign2')
-  , aws4 = require('aws4')
   , httpSignature = require('http-signature')
   , mime = require('mime-types')
   , stringstream = require('stringstream')
@@ -1232,6 +1231,7 @@ Request.prototype.aws = function (opts, now) {
   }
   
   if (opts.sign_version == 4 || opts.sign_version == '4') {
+    var aws4 = require('aws4')
     // use aws4  
     var options = {
       host: self.uri.host,