diff --git a/server.js b/server.js
index 8672988..6be73ec 100644
--- a/server.js
+++ b/server.js
@@ -45,6 +45,7 @@ app.get('/', function(req, res) {
     var width = 400;
     var seed = uuid();
     var canvas = composeImage(width, width, seed);
+    res.type('png');
     res.end(canvas.toBuffer(), 'binary');
 });
 
@@ -52,6 +53,7 @@ app.get('/:width', function(req, res) {
     var width = parseInt(req.params.width) || 400;
     var seed = uuid();
     var canvas = composeImage(width, width, seed);
+    res.type('png');
     res.end(canvas.toBuffer(), 'binary');
 });
 
@@ -59,6 +61,7 @@ app.get('/:width/:seed', function(req, res) {
     var width = parseInt(req.params.width) || 400;
     var seed = sanitize(req.params.seed) || uuid();
     var canvas = composeImage(width, width, seed);
+    res.type('png');
     res.end(canvas.toBuffer(), 'binary');
 });