diff --git a/server.js b/server.js
index 994664d..dcea871 100644
--- a/server.js
+++ b/server.js
@@ -4,43 +4,42 @@ try {
   console.error("WARNING unable to load newrelic")
 }
 
-var fs = require('fs');
-var express = require('express');
-var uuid = require('uuid/v4');
-var sanitize = require('sanitize-filename');
-var Canvas = require('canvas');
+const express = require('express');
+const uuid = require('uuid/v4');
+const sanitize = require('sanitize-filename');
+const Canvas = require('canvas');
 
-var Fox = require('./js/fox.js');
-var renderFox = require('./js/render-fox.js');
+const Fox = require('./js/fox.js');
+const renderFox = require('./js/render-fox.js');
 
 function composeImage(width, height, seed) {
     seed = seed || uuid();
-    var fox = Fox(width, height, seed);
-    var canvas = new Canvas(width, height);
-    var ctx = canvas.getContext('2d');
+    const fox = Fox(width, height, seed);
+    const canvas = new Canvas(width, height);
     renderFox(canvas, fox);
     return canvas;
 };
 
-var app = express();
+const app = express();
 
-var cacheTimeout = 60 * 60 * 24 * 30;
+const cacheTimeout = 60 * 60 * 24 * 30;
 
-app.get('/healthcheck', function(req, res) {
+app.get('/healthcheck', (req, res) => {
     res.status(200).end();
 });
 
-app.get('/:width/:seed', function(req, res) {
-    var width = parseInt(req.params.width) || 400;
+app.get('/:width/:seed', (req, res) => {
+    let width = parseInt(req.params.width) || 400;
     if (width > 400) width = 400;
-    var seed = sanitize(req.params.seed) || uuid();
-    var canvas = composeImage(width, width, seed);
-    var buffer = canvas.toBuffer();
+    const seed = sanitize(req.params.seed) || uuid();
+    const canvas = composeImage(width, width, seed);
+    const buffer = canvas.toBuffer();
     res.set('Cache-Control', 'max-age=' + cacheTimeout);
     res.set('Content-length', buffer.length);
     res.type('png');
     res.end(buffer, 'binary');
 });
 
-app.listen(process.env.PORT || 3000);
-console.log('listening on http://localhost:3000');
+app.listen(process.env.PORT || 3000, () => {
+    console.log('listening on http://localhost:3000');
+});