Where/how do you have your PB rear flasher mounted?

My rear rack is too high for it to be visibly mounted on the seatpost. There's no adequate spot on the rack to mount it without a creative hardware solution. I had it on my pannier, but it's the sort that has a pull over rain cover, which obscures the light when it's the most necessary. I usually just clip it to the waist of my pants, but that's a pretty inelegant solution.

I've seen some people have them strapped to their helmets, but I can't figure out how. Any ideas?