fabric.js cannot get the text aligned witht the textAlign

I cannot get the textAlign working in fabric.js The fontSize, fontBackground work properly, but not textAlign. Am I missing something?

var canvas = new fabric.Canvas('myCanvas');

$('button.addText').click(function() {
  var text = new fabric.Text($(this).siblings().val(), {
    textAlign: 'center',
    fontSize: 40
  });
  canvas.add(text);
});