Hi, I can't figure out the scansion of this line of Ovid: "protinus ut moriar, non ero, terra, tuus" (Tristia 4.10 line 130). I get protinus / ut mori / ar / non ero / terra tu / us, but then the "o" of "ero" is short when clearly it should be long (as far as I know, the only common Latin word with a short final "o" is "ego"). Is there something obvious I'm missing, or some obscure rule I don't know about? Any assistance (so that my brain can stop obsessing over this) would be much appreciated.