  Antiferromagnetic antiperovskites, of the form Mn$_3B$N ($B$ = Ni, Cu, Zn,
Sn, Ir, and Pt), have shown an outstanding behavior in which, giant negative
thermal expansion and chiral magnetic structures are intertwined. As such,
aiming to shed light on the magnetostructural behavior, related to the magnetic
ordering and structure of this type of materials, we studied by theoretical
first-principles calculations the spin-phonon coupling in the Manganese-based
antiperovskite Mn$_3$NiN, as a prototype in the Mn$_3B$N family. We found a
strong spin-lattice coupling by means of the understanding of the
phonon-dispersion curves obtained when including the chiral noncollinear
magnetic structure. To do so, we highlight the importance of the
exchange-correlation scheme selected and its influence on the electronic,
structural, and vibrational degrees of freedom. Finally, we found two unstable
vibrational modes at the $M$- and $R$-points when the magnetic ordering is
switched to ferromagnetic from the chiral $\Gamma_{4g}$ and $\Gamma_{5g}$. The
latter coupling was observed as a key signature of the strong spin-lattice
interaction.
