I would if it wouldn't cause the zipper to get stuck further down. For now I just use a ribbon tied through the zipper and around the snap at the top. No zipper catch on my boots
Maybe if you have a pull rage at the front use a paper clip to linn the zipper with the pull tab?
I have the same problem except with my leather gaters coming undone!! One minute they're on next they're hanging off my leg. It's happened to me twice now at shows hahaha - would love a solution to this too!