JavaScript prototype is not copied

For some reason, my classes written in CoffeeScript do not copy the prototype.

Here's the exact code I'm using:

module.exports = class ListQueue
  constructor: ->
    @queue = []
    @queueIds =[]
    @currentId = 0

  # Adds the given element to the queue.
  # Returns the index of the element.
  add: (el) ->
    @queueIds.push @currentId
    @queue.push el
    @currentId++ # return @lastIndex, then increment

  shift: ->
    @queueIndexes.shift()
    @queue.shift()

  # Returns the index in the @queue array for the given id.
  queueIndex: (id) ->
    for queueIndex, i in queueIndexes
      if queueIndex is id
        return i
    undefined

  get: (id) ->
    index = @queueIndex id
    @queue[index]

  length: ->
    @queue.length

  remove: (id) ->
    index = @queueIndex id
    if index?
      @queueIds = @queueIds.slice index, index
      @queue = @queue.slice index, index
      true
    else
      false

This is the prototype of the class, as expected:

  { add: [Function],
  shift: [Function],
  queueIndex: [Function],
  get: [Function],
  length: [Function],
  remove: [Function] }

But this is weird: new ListQueue actually gives me this:

  { queue: [], queueIds: [], currentId: 0 }

I'm using Node.JS 0.8.7.