The moral error theory has become increasingly popular in recent decades. So much so indeed that a new issue emerged, the so-called “now-what problem”: if all our moral beliefs are false, then what should we do with them? So far, philosophers who are interested in this problem have focused their attention on the mode of the attitudes we should have with respect to moral propositions. Some have argued that we should keep holding proper moral beliefs; others that we should replace our moral beliefs with fictional attitudes, beliefs in natural facts, or conative attitudes. But all these philosophers have set aside an important question about the content of these attitudes: which moral propositions, and more generally which moral theory, should we accept? The present paper addresses this neglected issue, arguing that moral error theorists should adopt a utilitarian moral fiction. In other words, they should accept the set of moral principles whose general acceptance would maximize overall well-being.