Error theories hold that judgments in a given domain(s) of discourse are false on account of the (putatively) systematically false beliefs underlying them. Companions-in-guilt arguments target a particular error theory, claiming that since domains of discourse not covered by said error theory are sufficiently similar to the domain(s) of discourse covered by the error theory, and yet the aforementioned domains of discourse seem in good standing, so too (on the pains of consistency) should the domain(s) attacked by the error theory be in good standing. Moral error theory is probably the error theory that has been paid most attention to. The epistemic reasons for belief companions-in-guilt argument is likewise probably the best known companions-in-guilt argument. Guy Fletcher (2017) argues that he has a new companions-in-guilt argument against moral error theory that is better than the epistemic reasons for belief companions-in-guilt argument, namely a prudential reasons for action companions-in-guilt argument. It is unclear how new Fletcher’s prudential reasons for action companions-in-guilt argument is, given Jonas Olson’s (2014) treatment of similar strands of thought in his landmark monograph on moral error theory. Regardless, Fletcher’s prudential reasons for action companions-in-guilt argument should (on the face of it) not worry the moral error theorist if said moral error theorist accepts Olson’s hypothetico-instrumentalist treatment of prudential reasons. But Bart Streumer’s (2017) new book offers an error theory about all normative judgments, such that even Olson’s hypothetico-instrumentalism is vulnerable to an error-theoretic critique; in some regard, Streumer’s ambitious error theory is a companions-in-guilt type critique of more limited error theories, such as Olson’s moral error theory. Streumer would bite the bullet, it appears, in response to Fletcher’s argument, but, were it not for the argument of Streumer’s book, it seems plausible that the moral error theorist could avail themselves of what presumably would be Olson’s response, and it is not at all clear that Streumer has decisively defeated Olson here. In this paper I assess the case Streumer offers against Olson’s hypothetico-instrumentalism, evaluating the prospects moving forward of Olson’s hypothetico-instrumentalism as a potential response to Fletcher.