diff --git a/index.js b/index.js
index 469c92c..d6eb59d 100644
--- a/index.js
+++ b/index.js
@@ -1,4 +1,4 @@
-var auth = require('./src/auth.middleware');
+const auth = require('./src/auth.middleware');
 
 module.exports = {
     auth
diff --git a/src/auth.middleware.js b/src/auth.middleware.js
index 5747934..fdae92b 100644
--- a/src/auth.middleware.js
+++ b/src/auth.middleware.js
@@ -1,9 +1,9 @@
-var admin = require.main.require('firebase-admin');
+const admin = require.main.require('firebase-admin');
 
-var logger = require('./util/logger');
+const logger = require('./util/logger');
 
 function firebaseAuthMiddleware(req, res, next) {
-    let authorization = req.header('Authorization');
+    const authorization = req.header('Authorization');
     if (authorization) {
         let token = authorization.split(' ');
         admin.auth().verifyIdToken(token[1])
diff --git a/src/util/logger.js b/src/util/logger.js
index 77ffed2..2413844 100644
--- a/src/util/logger.js
+++ b/src/util/logger.js
@@ -1,9 +1,9 @@
-var debug = (process.env.APP_DEBUG === 'true');
+const debug = (process.env.APP_DEBUG === 'true');
 
 function log() {
     if (!debug) return;
 
-    console.log.apply(null, arguments);
+    console.log(...arguments);
 }
 
 module.exports = {