Damage from a weapon with a modifier of -1

[Lil B]

I am GMing a game where the opponents are relatively weak right now doing damage of 1d4-1. If a 1 is rolled,is it damage of 1 or 0? I was thinking 1, but I'm questioning my decision.

[BltzKrg242]

Minimum Damage: If penalties reduce the damage result to less than 1, a hit still deals 1 point of nonlethal damage.