The factor here is used to divide, so the parameters have to be
switched; this has always been broken but probably before
3ca2bef76886450058d1667703aeafe4c2e456c3 nothing called this.
This also reverts 7bf1fa3757133f12cf6ca624f8cee6ba5363e7d8 because
that was a workaround for the problem in the wrong place.