We investigate the potential of future long baseline neutrino experiments at the task of resolving the $\theta_{23}$ octancy, that is, whether the atmospheric mixing angle lies in the high octant, where $\theta_{23} > 45^\circ$, or the low octant, where $\theta_{23} < 45^\circ$. We demonstrate the importance of the matter effects in the determination of the $\theta_{23}$ octant, and show with the GLoBES software how operating in neutrino and antineutrino modes contribute to the octant determination.