Node.js Module Loading Incompatibility

module_load_correct.js

/*This will work when loaded as module*/
exports.area = function(radius)	{
  return PI * radius * radius;
};

exports.circumference = function(radius)	{
  return PI * 2 * radius;
}

module_load_incorrect.js

/*This will not work when loaded as module*/
var exports = {};
var PI = 3.14;
exports.area = function(radius)	{
  return PI * radius * radius;
};

exports.circumference = function(radius)	{
  return PI * 2 * radius;
}

module_loader.js

var circle = require('./module_load_correct'), //module_load_incorrect
  sys = require('sys');

sys.puts('The area of circle with radius 4 is ' + circle.area(4));