Full Idea
Another view of counterfactuals (Lewis, Pollock, Stalnaker) is that they are true if at every possible world at which it is the case that p, and which is otherwise as similar as possible to the actual world, it is also the case that q.
Gist of Idea
Counterfactuals are true if in every world close to actual where p is the case, q is also the case
Source
Thomas Mautner (Penguin Dictionary of Philosophy [1996], p.114)
Book Reference
Mautner,Thomas: 'Dictionary of Philosophy' [Penguin 1997], p.114
A Reaction
This seems a good way if putting if, like Lewis, you actually believe in the reality of possible worlds, because then you are saying a counterfactual is made true by a set of facts. Otherwise it is not clear what the truth-maker is here.