diff --git a/lib/index.js b/lib/index.js
index 10ce4c3..573367f 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -94,7 +94,7 @@ module.exports = function connect(opts) {
 		}
 	}
 
-	async function handle_route(url, req, res) {
+	async function handle_route(url, req, res, next) {
 		// whatever happens, we're going to serve some HTML
 		res.set({
 			'Content-Type': 'text/html'
@@ -128,20 +128,7 @@ module.exports = function connect(opts) {
 
 					else {
 						const handler = mod[req.method.toLowerCase()];
-						if (handler) {
-							if (handler.length === 2) {
-								handler(req, res);
-							} else {
-								const data = await handler(req);
-
-								// TODO headers, error handling
-								if (typeof data === 'string') {
-									res.end(data);
-								} else {
-									res.end(JSON.stringify(data));
-								}
-							}
-						}
+						if (handler) handler(req, res, next);
 					}
 
 					return;
@@ -170,7 +157,7 @@ module.exports = function connect(opts) {
 		handle_index(url, req, res, () => {
 			handle_service_worker(url, req, res, () => {
 				handle_webpack_generated_files(url, req, res, () => {
-					handle_route(url, req, res);
+					handle_route(url, req, res, next);
 				});
 			});
 		});