Upper panel: $\pT$-differential production cross section of muons from heavy-flavour hadron decays for five rapidity intervals in the range $2.5 < y < 4$ in pp collisions at $\sqrt s$ = 5.02 TeV. Statistical uncertainties (bars) and systematic uncertainties (boxes) are shown. The production cross sections are compared with FONLL predictions . Bottom panel: ratios of the data to FONLL calculations. See the text for details.