In the Philosophical Investigations, Wittgenstein famously criticizes Frege’s conception of assertion. “Frege’s opinion that every assertion contains an assumption”, says Wittgenstein, rests on the possibility of parsing every assertoric sentence into two components: one expressing the assumption that is put forward for assertion, the other expressing that it is asserted. But this possibility does not entail that the “assertion consists of two acts, entertaining and asserting” - any more than the possibility of rendering assertions as pairs of questions and affirmative answers entails that they consist of questions. Frege scholars protest that such criticism is inappropriate, not only because Frege doesn’t speak about assumptions, but also - and crucially - because Wittgenstein fails to address the logical nature of assertion as reflected in Frege’s use of the judgment stroke. They seem to read Wittgenstein’s argument in the light of a remark in the Tractatus saying that the judgment stroke is “logically meaningless” because it simply indicates that the author holds the propositions marked with this sign to be true. In this paper, I argue that Wittgenstein’s criticism of Frege is not that the latter’s conception of judgment and assertion contains a corrupting psychological element. Rather, the criticism is that for Frege judgment and assertion are composed of two separate acts, i.e. an act of referring to a truth value and an act of determining which of the two it is. Through a detailed examination of the “black-spot analogy” in the Tractatus, I want to show that Wittgenstein presents a serious objection to Frege’s conception of judgment and assertion.