Forward-to-backward ratio of muons from heavy-flavour hadron decays as a fucntion of $\pt$ for p-Pb collisions at $\sqrt {s_{\rm NN}}$ = 5.02 TeV compared to model predictions [70]. Statistical uncertainties (bars), systematic uncertainties (open boxes) and normalisation uncertainties (filled box at $R_{\rm FB}^{\mu^\pm \leftarrow {\rm HF}}$ = 1) are shown.