Snap-to-grid problem

I'm using the following expression to get a 16x16 cursor to follow my mouse in a snap-to fashion...

cursor.x= int(mousex/16)*16

cursor.y= int(mousey/16)*16

It works fine and all, but the cursor tends to 'drag' behind a good bit when quickly moving the mouse. Is there any way to fix that?

Here are two topics about mouse lag that may be helpful.

http://www.scirra.com/forum/viewtopic.php?f=3&t=5154

http://www.scirra.com/forum/viewtopic.php?f=3&t=7771