diff --git a/lib/create-server.js b/lib/create-server.js
index 8ea28c8ec..6e4c0b225 100644
--- a/lib/create-server.js
+++ b/lib/create-server.js
@@ -8,9 +8,9 @@ var SolidWs = require('solid-ws')
 var debug = require('./debug')
 var createApp = require('./create-app')
 
-function createServer (argv) {
+function createServer (argv, app) {
   argv = argv || {}
-  var app = express()
+  app = app || express()
   var ldpApp = createApp(argv)
   var ldp = ldpApp.locals.ldp
   var mount = argv.mount || '/'