diff --git a/DDG4/lcio/LCIOConversions.cpp b/DDG4/lcio/LCIOConversions.cpp
index d1e747dbb5fb0d6f3f53a47c6e9dbeffd039de1e..607231a44d990445639bc25f365e76b698c2349f 100644
--- a/DDG4/lcio/LCIOConversions.cpp
+++ b/DDG4/lcio/LCIOConversions.cpp
@@ -35,7 +35,7 @@
 #include "UTIL/Operators.h"
 #include "UTIL/ILDConf.h"
 
-#include <G4SystemOfUnits.hh>
+#include "CLHEP/Units/SystemOfUnits.h"
 
 using namespace std;
 using namespace lcio ;
diff --git a/DDG4/plugins/Geant4ExtraParticles.cpp b/DDG4/plugins/Geant4ExtraParticles.cpp
index f9580d15a64ade349516ce9a58cbc562cc718b9a..c3533c71ecf52b2a266d4fc1afa55e6f6834bac3 100644
--- a/DDG4/plugins/Geant4ExtraParticles.cpp
+++ b/DDG4/plugins/Geant4ExtraParticles.cpp
@@ -24,10 +24,12 @@
 
 #include "G4ParticleTable.hh"
 #include "G4ParticleDefinition.hh"
-#include "G4SystemOfUnits.hh"
 #include "G4PhysicalConstants.hh"
 #include "G4Version.hh"
 
+#include "CLHEP/Units/SystemOfUnits.h"
+#include "CLHEP/Units/PhysicalConstants.h"
+
 #include <fstream>
 #include <sstream>
 #include <string>
@@ -91,18 +93,18 @@ void Geant4ExtraParticles::constructParticle(Constructor& ) {
     if(width<0) width = 0;
 
     // normalize to G4 units
-    mass *= GeV;
+    mass *= CLHEP::GeV;
 
     if (charge != 0) {
       charge /= 3.;
     }
 
     if (lifetime > 0) {
-      lifetime = lifetime*mm/c_light;
+      lifetime = lifetime*CLHEP::mm/CLHEP::c_light;
     }
 
     if (width == 0 && lifetime > 0) {
-      width = hbar_Planck/lifetime;
+      width = CLHEP::hbar_Planck/lifetime;
     }
 
     // don't add if the particle already exists