Fails with newer version of node (I'm using 6.9.4)

$ npm start

> beeportal@0.0.1 start /Users/kai/beeportal
> node server.js

/Users/kai/beeportal/server.js:3
var app = express.createServer();
^

TypeError: express.createServer is not a function
at Object. (/Users/kai/beeportal/server.js:3:19)
at Module._compile (module.js:570:32)
at Object.Module._extensions..js (module.js:579:10)
at Module.load (module.js:487:32)
at tryModuleLoad (module.js:446:12)
at Function.Module._load (module.js:438:3)
at Module.runMain (module.js:604:10)
at run (bootstrap_node.js:394:7)
at startup (bootstrap_node.js:149:9)
at bootstrap_node.js:509:3