node madness

sysPath=require('path');

files=['a','b','c'];
parent= "yo";

myjoin = function(a,b){return sysPath.join(a,b);}

console.log(files.map( myjoin.bind(null, parent) )); // works fine
console.log(files.map( sysPath.join.bind(null, parent) )); // throws exception

// [ 'yo/a', 'yo/b', 'yo/c'  ]
// path.js:488
// throw new TypeError('Arguments to path.join must be strings');