diff --git a/config.js b/config.js
index 3dfe020..45fc25e 100644
--- a/config.js
+++ b/config.js
@@ -30,8 +30,17 @@ if (process.env.AWS) {
 		'X-Content-Type-Options': 'nosniff',
 		'Access-Control-Allow-Origin': '*',
 		'Access-Control-Request-Method': 'GET',
-		'X-Powered-By': 'https://github.com/rich-Harris/packd',
+		'X-Powered-By': 'https://github.com/rich-harris/packd',
 		'Strict-Transport-Security': `max-age=${cacheExpiration}; includeSubDomains; preload`,
 	};
+
+	exports.onBadRequest = function (res) {
+		res.status( 200 );
+	};
+
+	exports.onError = function (res) {
+		// error will be propagated in the logs
+		res.status( 200 );
+	};
 }
 
diff --git a/package.json b/package.json
index 8f7ad06..e68e23c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "packd",
-  "version": "2.6.5",
+  "version": "2.6.6",
   "description": "Simple alternative to browserify-cdn",
   "scripts": {
     "start": "node server",
diff --git a/server/index.js b/server/index.js
index 8e9ae23..5ff877b 100644
--- a/server/index.js
+++ b/server/index.js
@@ -124,8 +124,6 @@ app.get( '/', ( req, res ) => {
 
 app.use( servePackage );
 
-// TODO 404
-
 app.listen( port, () => {
 	logger.log( `started at ${new Date().toUTCString()}` );
 	console.log( 'listening on localhost:' + port );
diff --git a/server/serve-package.js b/server/serve-package.js
index c5473a9..2fa7755 100644
--- a/server/serve-package.js
+++ b/server/serve-package.js
@@ -9,6 +9,7 @@ const cache = require( './cache.js' );
 const etag = require('etag');
 const sha1 = require('sha1');
 
+const { sendBadRequest, sendError } = require( './utils/responses.js' );
 const { root, registry, additionalBundleResHeaders } = require( '../config.js' );
 
 function stringify ( query ) {
@@ -23,9 +24,7 @@ module.exports = function servePackage ( req, res, next ) {
 
 	if ( !match ) {
 		// TODO make this prettier
-		res.status( 400 );
-		res.end( 'Invalid module ID' );
-		return;
+		return sendBadRequest(res, 'Invalid module ID' );
 	}
 
 	const user = match[1];
@@ -50,10 +49,7 @@ module.exports = function servePackage ( req, res, next ) {
 			if ( !meta.versions ) {
 				logger.error( `[${qualified}] invalid module` );
 
-				res.status( 400 );
-				res.end( 'invalid module' );
-
-				return;
+				return sendBadRequest(res, 'invalid module' );
 			}
 
 			const version = findVersion( meta, tag );
@@ -61,9 +57,7 @@ module.exports = function servePackage ( req, res, next ) {
 			if ( !semver.valid( version ) ) {
 				logger.error( `[${qualified}] invalid tag` );
 
-				res.status( 400 );
-				res.end( 'invalid tag' );
-				return;
+				return sendBadRequest(res, 'invalid tag' );
 			}
 
 			if ( version !== tag ) {
@@ -92,11 +86,10 @@ module.exports = function servePackage ( req, res, next ) {
 		})
 		.catch( err => {
 			logger.error( `[${qualified}] ${err.message}`, err.stack );
-			res.status( 500 );
 			const page = sander.readFileSync( `${root}/server/templates/500.html`, { encoding: 'utf-8' })
 				.replace( '__ERROR__', err.message );
 
-			res.end( page );
+			sendError(res, page);
 		});
 };
 
diff --git a/server/utils/responses.js b/server/utils/responses.js
new file mode 100644
index 0000000..2a2d1c7
--- /dev/null
+++ b/server/utils/responses.js
@@ -0,0 +1,21 @@
+const { onBadRequest, onError } = require( '../../config.js' );
+
+module.exports.sendBadRequest = function sendBadRequest (res, msg) {
+	res.status( 400 );
+
+	if (typeof onBadRequest === 'function') {
+		onBadRequest(res);
+	}
+
+	res.end( msg );
+};
+
+module.exports.sendError = function sendError (res, msg) {
+	res.status( 500 );
+
+	if (typeof onError === 'function') {
+		onError(res);
+	}
+
+	res.end( msg );
+};