AbstractThere has long been a suspicion that Kant's test for the universalizability of maxims can be easily subverted: instead of risking failing the test, design your maxim for any action whatsoever in a manner guaranteed to pass. This is the problem of maxim-fiddling. The present discussion of this problem has two theses:1]That extant approaches to maxim-fiddling are not satisfactory;2]That a satisfactory response to maxim-fiddling can be articulated using Kantian resources, especially the first two formulations of the categorical imperative.This approach to maxim-fiddling draws our attention to a Kantian notion of an offence against morality itself that has largely been overlooked.