diff --git a/lib/server.js b/lib/server.js
index <HASH>..<HASH> 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -72,7 +72,7 @@ const startServer = (config, callback) => {
       child.kill();
       return typeof cb === 'function' ? cb() : undefined;
     };
-    serverCb();
+    setTimeout(serverCb, 0);
     return child;
   } else {
     const opts = {noLog: true, path: publicPath};
Fix handling of custom servers. Closes GH-<I>