PS

*-nV - our; us (genitive and accusative pronominal suffix, 1 pl.) (Kogan 2009:69)

It is difficult to reconstruct the exact form of this pronominal suffix because of the vocalic differences in individual languages. A tendency to put the auslaut of the suffix into correlation with that of the nominative form of the pronoun is evident. That is why the data of languages, in which forms of the auslaut are different, are especially noteworthy: Akk. nīnu vs. -ni, Arb. naḥnu vs. -nā (according to T. Nöldeke and J. Barth, Arabic picture reflects the Proto-Semitic one). See Kogan 2009:69

Akkadian
-ni - our (genitive pronominal suffix, 1 pl.) (GAG § 42 g)
Hebrew
-nū - our; us (genitive and accusative pronominal suffix, 1 pl.) (Gesenius 1910:508)
Arabic
-nā - our; us (genitive and accusative pronominal suffix, 1 pl.) (Fischer 2002 § 268)
Geez
-na - our; us (genitive and accusative pronominal suffix) (CDG 380)
Tigre
-na - our; us (genitive and accusative pronominal suffix, 1 pl.) (WTS 323)
Tigrinya
-na - our; us (genitive and accusative pronominal suffix, 1 pl.) (Bulakh–Kogan 2013b:101)