  We compute the two-loop BSM contributions to the $h\longrightarrow
\gamma\gamma$ decay width in the aligned THDM. We adopt the simplifying
assumptions of vanishing EW gauge couplings and vanishing mass of the SM-like
Higgs boson, which allow us to exploit a low-energy theorem connecting the
$h\gamma\gamma$ amplitude to the derivative of the photon self-energy w.r.t.
the Higgs field. We briefly discuss the numerical impact of the newly-computed
contributions, showing that they may be required for a precise determination of
$\Gamma[h\rightarrow \gamma \gamma]$ in scenarios where the quartic Higgs
couplings are large.
