Title says it all. Any ideas?

Code:
D:\JumpStartNodeJs\nockmarket\nockmarket.js:42
  app.set('views', _dirname + '/views');
                   ^
ReferenceError: _dirname is not defined
    at HTTPServer.app.set.layout (D:\JumpStartNodeJs\nockmarket\nockmarket.js:42
:20)
    at HTTPServer.app.configure (D:\JumpStartNodeJs\nockmarket\node_modules\expr
ess\lib\http.js:542:61)
    at Object.<anonymous> (D:\JumpStartNodeJs\nockmarket\nockmarket.js:41:5)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
    at node.js:901:3

D:\JumpStartNodeJs\nockmarket>