diff --git a/src/launcher/start.js b/src/launcher/start.js
index 8ede17d..30ba94a 100644
--- a/src/launcher/start.js
+++ b/src/launcher/start.js
@@ -4,9 +4,10 @@ import ConnectCDP from '../lib/cdp.js';
 import InjectInto from './inject.js';
 
 const portRange = [ 10000, 60000 ];
+const generatePort = () => (Math.floor(Math.random() * (portRange[1] - portRange[0] + 1)) + portRange[0]);
 
 export default async (browserPath, args, transport, extra) => {
-  const port = transport === 'websocket' ? (Math.floor(Math.random() * (portRange[1] - portRange[0] + 1)) + portRange[0]) : null;
+  const port = transport === 'websocket' ? generatePort() : null;
 
   const proc = spawn(browserPath, [
     transport === 'stdio' ? `--remote-debugging-pipe` : `--remote-debugging-port=${port}`,