  We study subleading corrections to the genus-zero free energy of the
$\mathcal{N}=3$ Gaiotto-Tomasiello theory. In general, we obtain the endpoints
and free energy as a set of parametric equations via contour integrals of the
planar resolvent, up to exponentially suppressed corrections. In the particular
case that the two gauge groups in the quiver are of equal rank, we find an
explicit (perturbative) expansion for the free energy. If, additionally, both
groups have equal levels, then we find the full expression for the genus-zero
free energy, modulo exponentially suppressed corrections. We also verify our
results numerically.
