The “small improvement problem” (“the Problem”) applies when no option in a comparison is best nor, it seems, are the options equal, because a small improvement to one would fail to make it the better choice. I argue that vagueness causes the Problem, such that the options are vaguely equal or vaguely “related.” I then unpack an important instance of the Problem, the comparison between a crime and a punishment upon which the ideal of a retributively deserved sentence is based. I argue that this comparison is not only vague, but remarkably vague, leading to an expansive array of “not undeserved” sentences. I conclude, however, that retributivism can only justify the least harmful “not undeserved” sentence.