This article studies some instances of the addition of διαστολή in the Codex Vaticanus gr. 1209. This addition may also be observed in some passages of the New Testament and the Lxx where the pronominal ὅτι is used. The article affirms that in the passages examined, the addition is more for philological than for reading reasons. Διαστολή could in fact be a kind of accidental signature that helps to fix or confirm fixed points before the codex came to the Vatican Library in 1475.