  The impact of the three-loop effects of order $\alpha_t\alpha_s^2$ on the
mass of the light CP-even Higgs boson in the MSSM is studied in a pure
$\overline{\text{DR}}$ context. For this purpose, we implement the results of
Kant et al. into the C++ module Himalaya and link it to FlexibleSUSY, a
Mathematica and C++ package to create spectrum generators for BSM models. The
three-loop result is compared to the fixed-order two-loop calculations of the
original FlexibleSUSY and of FeynHiggs, as well as to the result based on an
EFT approach. Aside from the expected reduction of the renormalization scale
dependence with respect to the lower order results, we find that the three-loop
contributions significantly reduce the difference from the EFT prediction in
the TeV-region of the SUSY scale $M_S$. Himalaya can be linked also to other
two-loop $\overline{\text{DR}}$ codes, thus allowing for the elevation of these
codes to the three-loop level.
