diff --git a/FDTD/extensions/operator_extension.cpp b/FDTD/extensions/operator_extension.cpp
index 1f5d14b..60f09e0 100644
--- a/FDTD/extensions/operator_extension.cpp
+++ b/FDTD/extensions/operator_extension.cpp
@@ -34,16 +34,10 @@ Operator_Extension::Operator_Extension(Operator* op, Operator_Extension* op_ext)
 {
 	UNUSED(op_ext);
 	m_Op = op;
+	m_Op_Cyl = dynamic_cast<Operator_Cylinder*>(op);
 }
 
 void Operator_Extension::ShowStat(ostream &ostr) const
 {
 	ostr << "--- " << GetExtensionName() << " ---" << endl;
 }
-
-Operator_Extension* Operator_Extension::Clone(Operator* op)
-{
-	if (dynamic_cast<Operator_Extension*>(this)==NULL)
-		return NULL;
-	return new Operator_Extension(op, this);
-}
diff --git a/FDTD/extensions/operator_extension.h b/FDTD/extensions/operator_extension.h
index 0856377..92c518b 100644
--- a/FDTD/extensions/operator_extension.h
+++ b/FDTD/extensions/operator_extension.h
@@ -44,7 +44,7 @@ public:
 		Create a clone of this extension, will return NULL if this is impossible (e.g. derived extension has no clone method and copy-constructor)...
 		BuildExtension has to be called separatly!
 	*/
-	virtual Operator_Extension* Clone(Operator* op);
+	virtual Operator_Extension* Clone(Operator* op) {return NULL;}
 
 	virtual bool BuildExtension() {return true;}