This paper combines philological, linguistic, and paleographical methods in order to analyse 458 ‘asigmatic’ forms ending in -a (1st decl.), -o (2nd decl.), and -e/-i (3rd decl.) instead of the expected ‘sigmatic’ plurals ending in -as, -os, and -es, respectively. The forms are from a corpus of eighth- and ninth-century Tuscian charters. First, we discuss potential extra-linguistic causes that may have provoked an erroneous omission of -s; second, we examine the cases which may well represent other Late Latin grammatical forms rather than genuine asigmatic plurals. We argue that once errors and otherwise explicable forms have been removed, the rest can be considered intermediate, asigmatic, stages of the plural -V1 in the chain -V1s → -V1 → -V2 (e.g., CL casas → casa → It. case).