diff --git a/DDG4/edm4hep/Geant4Output2EDM4hep.cpp b/DDG4/edm4hep/Geant4Output2EDM4hep.cpp
index ca33873ccd407ec3885edb84188ae1ea7618d6f6..bc7abd5e61c29d3f1967febee379159760fac328 100644
--- a/DDG4/edm4hep/Geant4Output2EDM4hep.cpp
+++ b/DDG4/edm4hep/Geant4Output2EDM4hep.cpp
@@ -25,7 +25,8 @@
 // Geant4 headers
 #include "G4Threading.hh"
 #include "G4AutoLock.hh"
-#include <G4Version.hh>
+#include "G4Version.hh"
+#include "G4SystemOfUnits.hh"
 
 // edm4hep include files
 #include "edm4hep/EventHeaderCollection.h"