  The charged-Higgs-mediated contribution to the Wilson coefficient of the
$b\to s\gamma$ magnetic penguin is expected to be one of the more promising
candidates for a supersymmetric effect in B physics, probably the only one in
gauge-mediated models. We compute the two-loop QCD correction to it. With naive
dimensional regularization and MSbar subtraction, for reasonable values of the
charged Higgs mass and for mu-bar = m_top, we find a (10--20)% reduction of the
corresponding one-loop effect.
