diff --git a/lib/server.js b/lib/server.js
index 49cf340..372c238 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -46,7 +46,8 @@ class Server {
 
         res.writeHead(200, {
           'Content-Type': 'image/png',
-          'Content-Length': buf.length
+          'Content-Length': buf.length,
+          'Cache-Control': 'maxage=604800' // Cache hashed favicon for 7 days
         }).end(buf)
 
         return