Abstract: Abstract The Khotanese and Sogdian genitive plural endings cannot be satisfactorily explained from the traditionally posited ending *- nām . Instead, Khotanese - nu and Sogdian - nw point to *- nam . Instead of assuming a special rule that shortens the expected *- nām to *- nam , it is argued that the evidence from East Iranian is to be taken at face value. A short ending *- om can be reconstructed for Proto-Indo-European as well and the East Iranian reflexes of a short ending are probably an archaism.