diff --git a/trunk/paradiseo-mo/src/memory/moDiversification.h b/trunk/paradiseo-mo/src/memory/moDiversification.h
index 5dffc2a41..dee5c068e 100644
--- a/trunk/paradiseo-mo/src/memory/moDiversification.h
+++ b/trunk/paradiseo-mo/src/memory/moDiversification.h
@@ -8,7 +8,7 @@
  * Abstract class for diversification strategy
  */
 template< class Neighbor >
-class moDiversification : public moMemory<Neighbor>, public eoUF<typename Neighbor::EOT &,bool>
+class moDiversification : virtual public moMemory<Neighbor>, public eoUF<typename Neighbor::EOT &,bool>
     {};
 
 #endif
diff --git a/trunk/paradiseo-mo/src/memory/moIntensification.h b/trunk/paradiseo-mo/src/memory/moIntensification.h
index c1c21274f..ca69d066b 100644
--- a/trunk/paradiseo-mo/src/memory/moIntensification.h
+++ b/trunk/paradiseo-mo/src/memory/moIntensification.h
@@ -8,7 +8,7 @@
  * Abstract class for intensification strategy
  */
 template< class Neighbor >
-class moIntensification : public moMemory<Neighbor>, public eoUF<typename Neighbor::EOT &,bool>
+class moIntensification : virtual public moMemory<Neighbor>, public eoUF<typename Neighbor::EOT &,bool>
     {};
 
 #endif