diff --git a/README.mkdn b/README.mkdn
index b43e5b1..9d5fcee 100644
--- a/README.mkdn
+++ b/README.mkdn
@@ -7,11 +7,11 @@ But this module can work on browsers.
 Usage
 ------
 
-    var ma = require('mobileagent.js'),
+    var MobileAgent = require('../mobileagent.js'),
         http = require('http');
 
     http.createServer(function (req, res) {
-        var ma = ma.getMobileAgent(req);
+        var ma = MobileAgent.getMobileAgent(req);
 
         res.writeHead(200, {'Content-Type': 'text/plain'});
         res.end('Hello ' + ma.getCarrierLongName() + '\n');
diff --git a/eg/server.js b/eg/server.js
index 53790ca..d17bd37 100644
--- a/eg/server.js
+++ b/eg/server.js
@@ -1,8 +1,8 @@
-var ma = require('../mobileagent.js'),
+var MobileAgent = require('../mobileagent.js'),
     http = require('http');
 
 http.createServer(function (req, res) {
-    var ma = ma.getMobileAgent(req);
+    var ma = MobileAgent.getMobileAgent(req);
 
     res.writeHead(200, {'Content-Type': 'text/plain'});
     res.end('Hello ' + ma.getCarrierLongName() + '\n');
diff --git a/mobileagent.js b/mobileagent.js
index 539110f..b92cc6e 100644
--- a/mobileagent.js
+++ b/mobileagent.js
@@ -455,19 +455,29 @@ var MobileAgentNonMobile = MobileAgentBase.extend({
  * @param req request object. It is normally node.js' HTTP request.
  **/
 function getMobileAgent(req) {
-    var ua = req['user-agent'],
-        carrier = detectCarrier(ua);
-    switch (carrier) {
+    var ua,
+        headers,
+        carrier;
+    if (typeof req === 'object') {
+        if ('headers' in req) {
+            headers = req['headers'];
+        } else {
+            headers = req;
+        }
+    } else {
+        headers = { 'user-agent': req }; // plain string
+    }
+    switch (detectCarrier(headers['user-agent'])) {
     case 'I':
-        return new MobileAgentDoCoMo(req);
+        return new MobileAgentDoCoMo(headers);
     case 'V':
-        return new MobileAgentSoftBank(req);
+        return new MobileAgentSoftBank(headers);
     case 'E':
-        return new MobileAgentEZWeb(req);
+        return new MobileAgentEZWeb(headers);
     case 'H':
-        return new MobileAgentAirHPhone(req);
+        return new MobileAgentAirHPhone(headers);
     default:
-        return new MobileAgentNonMobile(req);
+        return new MobileAgentNonMobile(headers);
     }
 }