[NTG-context] Controlling the space between the number and the title in heads

Hi, How to control the space between the number and the title in heads? By default it seems there is a space of about 1 em. I want to change that space and set a normal space instead (a word space), since I've put a dot stopper after the numbers (\setupheads[stopper=.]). Example: 1. Title (what I get) 1. Title (what I want)