diff --git a/.babelrc b/.babelrc
new file mode 100644
index 0000000..002b4aa
--- /dev/null
+++ b/.babelrc
@@ -0,0 +1,3 @@
+{
+  "presets": ["env"]
+}
diff --git a/index.js b/index.js
deleted file mode 100644
index d6eb59d..0000000
--- a/index.js
+++ /dev/null
@@ -1,5 +0,0 @@
-const auth = require('./src/auth.middleware');
-
-module.exports = {
-    auth
-};
diff --git a/lib/auth.middleware.js b/lib/auth.middleware.js
new file mode 100644
index 0000000..2dfdb67
--- /dev/null
+++ b/lib/auth.middleware.js
@@ -0,0 +1,25 @@
+'use strict';
+
+var admin = require.main.require('firebase-admin');
+
+var logger = require('./util/logger');
+
+function firebaseAuthMiddleware(req, res, next) {
+    var authorization = req.header('Authorization');
+    if (authorization) {
+        var token = authorization.split(' ');
+        admin.auth().verifyIdToken(token[1]).then(function (decodedToken) {
+            logger.log(decodedToken);
+            res.locals.user = decodedToken;
+            next();
+        }).catch(function (err) {
+            logger.log(err);
+            res.sendStatus(401);
+        });
+    } else {
+        logger.log('Authorization header is not found');
+        res.sendStatus(401);
+    }
+}
+
+module.exports = firebaseAuthMiddleware;
\ No newline at end of file
diff --git a/lib/index.js b/lib/index.js
new file mode 100644
index 0000000..e7d5966
--- /dev/null
+++ b/lib/index.js
@@ -0,0 +1,7 @@
+'use strict';
+
+var auth = require('./auth.middleware');
+
+module.exports = {
+    auth: auth
+};
\ No newline at end of file
diff --git a/lib/util/logger.js b/lib/util/logger.js
new file mode 100644
index 0000000..0e3e792
--- /dev/null
+++ b/lib/util/logger.js
@@ -0,0 +1,15 @@
+'use strict';
+
+var debug = process.env.APP_DEBUG === 'true';
+
+function log() {
+    var _console;
+
+    if (!debug) return;
+
+    (_console = console).log.apply(_console, arguments);
+}
+
+module.exports = {
+    log: log
+};
\ No newline at end of file
diff --git a/package.json b/package.json
index e3851f9..95c6a24 100644
--- a/package.json
+++ b/package.json
@@ -2,8 +2,12 @@
   "name": "express-firebase-middleware",
   "version": "1.0.0",
   "description": "Express middleware for your Firebase applications",
-  "main": "index.js",
+  "main": "lib/index.js",
+  "files": [
+    "lib"
+  ],
   "scripts": {
+    "build": "babel src -d lib --ignore spec.js",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "repository": {
@@ -23,7 +27,13 @@
   },
   "homepage": "https://github.com/antonybudianto/express-firebase-middleware#readme",
   "peerDependencies": {
-    "express": "^4.15.0",
-    "firebase-admin": "^4.1.2"
+    "express": "^4.16.2",
+    "firebase-admin": "^5.5.0"
+  },
+  "devDependencies": {
+    "babel-cli": "^6.26.0",
+    "babel-core": "^6.26.0",
+    "babel-preset-env": "^1.6.1",
+    "np": "^2.17.0"
   }
 }
diff --git a/src/index.js b/src/index.js
new file mode 100644
index 0000000..b422b64
--- /dev/null
+++ b/src/index.js
@@ -0,0 +1,5 @@
+const auth = require('./auth.middleware');
+
+module.exports = {
+    auth
+};