diff --git a/server.js b/server.js
index d758616..aa35794 100644
--- a/server.js
+++ b/server.js
@@ -46,11 +46,14 @@ var app = express();
 
 app.use(express.static(__dirname + '/images'));
 
+var cacheTimeout = 60 * 60 * 24 * 30;
+
 app.get('/', function(req, res) {
     var width = 400;
     var seed = uuid();
     var canvas = composeImage(width, width, seed);
     var buffer = canvas.toBuffer();
+    res.set('Cache-Control', 'max-age=' + cacheTimeout);
     res.set('Content-length', buffer.length);
     res.type('png');
     res.end(buffer, 'binary');
@@ -65,6 +68,7 @@ app.get('/:width', function(req, res) {
     var seed = uuid();
     var canvas = composeImage(width, width, seed);
     var buffer = canvas.toBuffer();
+    res.set('Cache-Control', 'max-age=' + cacheTimeout);
     res.set('Content-length', buffer.length);
     res.type('png');
     res.end(buffer, 'binary');
@@ -75,6 +79,7 @@ app.get('/:width/:seed', function(req, res) {
     var seed = sanitize(req.params.seed) || uuid();
     var canvas = composeImage(width, width, seed);
     var buffer = canvas.toBuffer();
+    res.set('Cache-Control', 'max-age=' + cacheTimeout);
     res.set('Content-length', buffer.length);
     res.type('png');
     res.end(buffer, 'binary');