Nuclear modification factor ($R_{\text{pA}}$) of isolated prompt photon production in p--Pb collisions at $\snn=5.02$ and \SI{8.16}{TeV} shown together with a measurement by the ATLAS collaboration in p--Pb collisions at $\snn=\SI{8.16}{TeV}$ . For illustration purposes, the data points at $\sqrt{s_{\text{NN}}}=\SI{5.02}{TeV}$ are displaced by $\Delta p_{\rm T}=+\SI{300}{MeV}/c$. The normalisation uncertainties are denoted as coloured boxes around unity.