This article discusses the authorship and content of a number of marginal annotations made to a copy of Ascanio Condivi's 1553 Life of Michelangelo. The annotations are shown here to be the work of the artist's last assistant, Tiberio Calcagni, and were probably written into the book c. 1563-64, some of them predating and some postdating the master's death. They record Michelangelo's reactions to mistakes in Condivi's account, as well as confirm the veracity of some of the "tall stories" found in the biography.