Is there a reason to not nest the checkbox inside the label? I have always put them next to the checkbox until very recently, when I was trying to increase clic

Is there a reason to not nest the checkbox inside the label? I have always put them next to the checkbox until very recently, when I was trying to increase clickable area. I've found it ends up working much better than putting it beside, covering the area around the checkbox, too! Is this "improper HTML"?