David Tripp argues that the present sequence of Irenaeus's Against Heresies, book one, does not follow the original order. A close analysis of his argument finds it mostly deficient. But Tripp has identified a genuine discrepancy between books one and two. I suggest two possible ways of resolving it. Either Irenaeus did not accurately recapitulate the contents of book one in his preface to book two or he wrote book one in two drafts: he first refuted only the Valentinians, but then turned the material into a global heresiology. I suggest the second solution should be taken more seriously since it explains a number of other peculiar features of Against Heresies.