In this talk I present a model of light dark matter whose relic abundance was set during a period of resonantly enhanced interactions with the Standard Model through the Higgs portal. This is a new application of dark matter with temperature-dependent mass due to a phase transition in the dark sector. During the phase transition, the dark matter mass decreases with temperature and at some point in its cosmological history scans through the Higgs resonance. This reopens the possibility of Higgs portal dark matter with sub-GeV masses observed today, as portal couplings consistent with existing constraints can still be used to reproduce the relic abundance.
