A new platinum-catalysed dihydroalkoxylation of allenes is described to give aliphatic acetals by an unexpected attack of two molecules of methanol to the terminal carbon of the allene moiety. Deuteration experiments suggest an unprecedented formal 1,3-dipolar addition of methanol to a zwitterionic platinum carbene as the key step. The first platinum-catalysed intermolecular carbon-based nucleophile addition to allenes is also reported.