How to work properly with event listeners in CoffeeScript classes

gistfile1.coffee

class SomeClass
  constructor: ->
    @message = 'Page scrolled'
    
    window.addEventListener 'scroll', @onPageScrolled, no
  
  # note I'm using a fat arrow (check how the compiler handle it)
  onPageScrolled: =>
    alert @message
  
  shutUp: ->
    window.removeEventListener 'scroll', @onPageScrolled, no