diff --git a/DDG4/include/DDG4/Geant4PrimaryHandler.h b/DDG4/include/DDG4/Geant4PrimaryHandler.h
index b4a098ab402fd54f02260558508d778258af7930..c71444140dc7886cf6623d981c4758e3e3d865fa 100644
--- a/DDG4/include/DDG4/Geant4PrimaryHandler.h
+++ b/DDG4/include/DDG4/Geant4PrimaryHandler.h
@@ -58,7 +58,7 @@ namespace dd4hep {
       virtual void operator()(G4Event* event);
 
     public:
-      Geant4PrimaryConfig m_primaryConfig;
+      Geant4PrimaryConfig m_primaryConfig{};
 
     };
   }    // End namespace sim