diff --git a/index.js b/index.js
index 390dc2f..35fed7c 100644
--- a/index.js
+++ b/index.js
@@ -519,10 +519,14 @@ function Server (opts) {
   }
 }
 
-Server.prototype.listen = function (port) {
+Server.prototype.listen = function (port, onlistening) {
   var self = this
   var tasks = []
 
+  if (onlistening) {
+    self.once('listening', onlistening)
+  }
+
   self._httpServer && tasks.push(function (cb) {
     self._httpServer.listen(port, cb)
   })