In this talk I report on progress towards the computation of the next-to-next-to-leading order virtual corrections to Higgs boson pair production in gluon fusion, in an expansion around the forward-scattering limit. The results of this computation will provide an estimate of the size and uncertainty of the three-loop virtual corrections in a comparatively much larger region of phase space than the results available in the literature, which are based on an expansion in the limit of a large top quark mass.