The muon anomalous magnetic moment and its most recent measurement at Fermilab has made headlines on April 7th, together with a (not entirely justified) claim that the new experimental value differs from the theoretical value by 4.2 sigma. It turns out that, at the required level of precision, hadronic contributions to the muon g-2 are relevant, and these are notoriously difficult to calculate from theory. The theoretical determinations of the hadronic contributions to g-2 fall under two broad categories: the dispersive approach and lattice simulations. Both approaches are systematic dominated, but the systematics are very different in the two cases. In this talk I will focus on one particular source of systematic error for lattice calculations, i.e. finite volume effects to the hadron vacuum polarization contribution to g-2. I will review the relevance of this problem, the theoretical techniques that one can use to approach it, and I will discuss the results.