The anomalous magnetic moment (g-2) is one of the most precisely measured quantities in fundamental physics. Currently there is a discrepancy between its experimental value and standard-model predictions of three to four standard deviations. This may be a hint of new physics and demands for further investigation. The dominant uncertainties on the theory side are the hadronic vacuum polarization (HVP) and hadronic light-by-light (HLbL) contributions. This talk will explain the lattice QCD position-space approach to HLbL scattering in the muon g-2 developed in Mainz.