  In this proceeding we present the impact of the EW corrections on $t \bar t$
distributions focusing on the effect of the photon PDF. We use the {\sc
NNPDF2.3QED} and {\sc CT14QED} PDF sets, which include the photon PDF. We
discuss a detailed comparison between the results obtained from these two PDF
sets at NLO QCD+EW accuracy for 13 TeV, focusing on the top-quark $p_T$ and the
top-quark pair rapidity. We point out the differences between these two PDF
sets and we show that the rapidity of the top-quark pair can be used in order
to constrain the photon PDF predicted by the {\sc NNPDF2.3QED} set.
