Stop being auto-subscribed to GitHub repositories from an organisation

I’ve been joined to a GitHub “organisation” for some things I do at the day job occasionally (administrative and Debian packaging things). I’m not normally involved in the development of the stuff hosted by that GitHub organisation.

However, when someone creates a new repository on that organisation, I am automatically subscribed to it and need to manually unwatch it, all the time.

How can I stop being automatically subscribed to new repositories—ideally, for one particular organisation only?