Heegaard Floer homology was originally defined over the integers by Ozsvath and Szabo using choices of coherent orientations on the moduli spaces. In this talk I will explain how to construct orientations in a more canonical way, by using a coupled Spin structure on the Lagrangian tori. This allows us to prove naturality of Heegaard Floer homology over the integers. The talk is based on joint work with Mohammed Abouzaid.