diff --git a/lib/styleguide.js b/lib/styleguide.js
index 7c11b1d2..a4fb3855 100644
--- a/lib/styleguide.js
+++ b/lib/styleguide.js
@@ -505,13 +505,16 @@ module.exports.server = function(options) {
 };
 
 function startServer(options) {
-  // Ignore start server if we already have instance running
+  // Ignore start server if we already have instance running on the same port
   if (!serverInstance) {
+    serverInstance = {};
+  }
+  if (!serverInstance[options.port]) {
     var port = options.port;
-    serverInstance = sgServer(options);
-    serverInstance.app.set('port', port);
-    serverInstance.server.listen(serverInstance.app.get('port'), function() {
-      console.log('Express server listening on port ' + serverInstance.server.address().port);
+    serverInstance[port] = sgServer(options);
+    serverInstance[port].app.set('port', port);
+    serverInstance[port].server.listen(serverInstance[port].app.get('port'), function() {
+      console.log('Express server listening on port ' + serverInstance[port].server.address().port);
     }).on('error', function(error) {
       if (error.code === 'EADDRINUSE') {
         console.error('Port:' + port + ' is already in use.');
@@ -519,7 +522,7 @@ function startServer(options) {
       }
     });
   }
-  return serverInstance;
+  return serverInstance[options.port];
 }
 
 module.exports.addSection = addSection;