diff --git a/corsika/modules/proposal/HadronicPhotonModel.hpp b/corsika/modules/proposal/HadronicPhotonModel.hpp
index f021ab508b7d8cecbbbb8cc105f0f23cae4229da..6fe6b88bbcc46f47ee93f0fe9848ca5c66f58999 100644
--- a/corsika/modules/proposal/HadronicPhotonModel.hpp
+++ b/corsika/modules/proposal/HadronicPhotonModel.hpp
@@ -38,7 +38,7 @@ namespace corsika::proposal {
     inline static auto logger_{get_logger("corsika_proposal_HadronicPhotonModel")};
     THadronicModel& heHadronicInteraction_;
     //! threshold for high energy hadronic interaction model. Lab. energy per nucleon
-    HEPEnergyType heHadronicModelThresholdLabNN_;
+    HEPEnergyType const heHadronicModelThresholdLabNN_;
   };
 } // namespace corsika::proposal
 
diff --git a/tests/modules/testProposal.cpp b/tests/modules/testProposal.cpp
index 8b74c87af36dbf11e2f6d50d91970a360adaf843..eb186c3582d9c4efbfec8fa7b2dab8bfdb09de15 100644
--- a/tests/modules/testProposal.cpp
+++ b/tests/modules/testProposal.cpp
@@ -42,10 +42,7 @@ public:
     }
   }
   bool constexpr isValid(Code const, Code const, HEPEnergyType const sqrsNN) const {
-    if (sqrsNN < 10_GeV)
-      return false;
-    else
-      return true;
+    return (sqrsNN >= 10_GeV);
   };
 };