diff -u -r1.5 -r1.6
--- LCFourVector.h	29 Nov 2005 19:55:34 -0000	1.5
+++ LCFourVector.h	22 Mar 2006 11:53:22 -0000	1.6
@@ -1,13 +1,18 @@

 // -*- C++ -*-
 #ifdef CLHEP  // only if CLHEP is available !
 

-#ifndef UTIL_LCFOURVECTOR_H
-#define UTIL_LCFOURVECTOR_H 1

+#ifndef UTIL_LCFourVector_H
+#define UTIL_LCFourVector_H 1

 
 #include "EVENT/LCObject.h"
 #include "CLHEP/Vector/LorentzVector.h"
 
 

+// CLHEP 1.9 and higher introduce a namespace:
+namespace CLHEP{}  
+using namespace CLHEP ;
+
+

 namespace UTIL {