The knowledge account of assertion (KAA) is the view that assertion is governed by the norm that the speaker should know what s/he asserts. It is not the purpose of this article to examine all the criticisms nor to try to give a full defence of KAA, but only to defend it against the charge of being normatively incorrect. It has been objected that assertion is governed by other norms than knowledge, or by no norm at all. It seems to me, however, that a number of these criticisms are based on a number of misunderstandings of the notion of a norm and of the way it can regulated a given practice. Once we spell out in what sense knowledge can play a normative role in this context, the KAA appears much more plausible.