Kennen's Electrical Surge Passive

So playing Kennen I noticed that if his electrical surge attack is ready but the attack is cancelled in some way, target dies or you cancel it yourself, the passive is used up still. Other camps with similar auto attack modifiers like twisted fates stacked deck are not consumed when the auto attack is cancelled. I hope this inconsistency is just an oversight as it can be very annoying to have the extra damage be eaten up by incomplete attacks.