diff --git a/Solver/functionSpace.h b/Solver/functionSpace.h
index f27a850a3bd51c6f9cb02fdd41366667eca9cb98..460599d4313337e472b7a1ef3c56a7f8b82bdf96 100644
--- a/Solver/functionSpace.h
+++ b/Solver/functionSpace.h
@@ -69,6 +69,7 @@ class FunctionSpaceBase
   virtual ~FunctionSpaceBase(){}
   virtual int getNumKeys(MElement *ele) = 0; // if one needs the number of dofs
   virtual void getKeys(MElement *ele, std::vector<Dof> &keys) = 0;
+  virtual FunctionSpaceBase* clone(const std::vector<int>& comp) const {return NULL;}
 };
 
 template<class T>