The News and Views article “Millennium bug” by R. S. Siew — published on 1 April (Nature 398, 376; 1999) — was, we can confirm, an April fool. Most of the references, such as the citation of Sisir, C. and Lainnellim, K. Silico (in press) on the crucial Y2K mutation, are figments of the author's backward thinking. G. K. Chesterton, cited as having published a paper in Protista in 1997, in fact died in 1936, and as far as we are aware did no research in this field.