`minecraft:set_damage` item modifier acting strange

I'm messing around with some items and I am trying to use an item modifier to bring an item's damage down by one using this item modifier: [ { "function": "minecraft:set_damage", "damage": -0.04, "add": true } ] It seems like it should work, but it refuses to bring the damage value down after the item reaches 21 durability. (the item is made to have a max damage value using components, it has a max damage of 25.)