diff --git a/corsika/modules/proposal/ProposalProcessBase.hpp b/corsika/modules/proposal/ProposalProcessBase.hpp
index 666fff2eaf6737e35b605653a0bdd86669d7b0cf..0f13f54b4c2b8303b75afca262c67d761d7165c2 100644
--- a/corsika/modules/proposal/ProposalProcessBase.hpp
+++ b/corsika/modules/proposal/ProposalProcessBase.hpp
@@ -111,6 +111,10 @@ namespace corsika::proposal {
             PROPOSAL::make_crosssection(PROPOSAL::crosssection::PhotoeffectSauter{},
                                         particle_def, medium, nullptr, interpolate);
         cross_vec.push_back(std::move(photoeffect));
+        auto muonpair = PROPOSAL::make_crosssection(
+            PROPOSAL::crosssection::PhotoMuPairBurkhardtKelnerKokoulin{}, particle_def,
+            medium, nullptr, interpolate);
+        cross_vec.push_back(std::move(muonpair));
         return cross_vec;
       };