diff --git a/DDG4/include/DDG4/Geant4FastSimShowerModel.inl.h b/DDG4/include/DDG4/Geant4FastSimShowerModel.inl.h
index 7faea69cdd98db7b664b84fe9b65dd7e621b6418..6da7cbb449decc71a13831961e8b3123d867db6b 100644
--- a/DDG4/include/DDG4/Geant4FastSimShowerModel.inl.h
+++ b/DDG4/include/DDG4/Geant4FastSimShowerModel.inl.h
@@ -90,6 +90,7 @@ namespace dd4hep  {
 #if G4VERSION_NUMBER > 1070
 #include "G4FastSimHitMaker.hh"
 #else
+class G4FastHit;
 class G4FastSimHitMaker  {  public:  void make(const G4FastHit&, const G4FastTrack&)  { } };
 #endif