diff --git a/src/middleware.ts b/src/middleware.ts
index 15b4bbf..bab6536 100644
--- a/src/middleware.ts
+++ b/src/middleware.ts
@@ -151,7 +151,7 @@ export default function middleware(opts: {
 
 		serve({
 			prefix: '/client/',
-			cache_control: dev() ? 'no-cache' : 'max-age=31536000'
+			cache_control: dev() ? 'no-cache' : 'max-age=31536000, immutable'
 		}),
 
 		get_server_route_handler(manifest.server_routes),