diff --git a/FDTD/operator_extension.cpp b/FDTD/operator_extension.cpp
index cc3b3bc..4a52a93 100644
--- a/FDTD/operator_extension.cpp
+++ b/FDTD/operator_extension.cpp
@@ -24,6 +24,10 @@ Operator_Extension::Operator_Extension(Operator* op)
 	m_Op = op;
 }
 
+Operator_Extension::~Operator_Extension()
+{
+}
+
 Operator_Extension::Operator_Extension(Operator* op, Operator_Extension* op_ext)
 {
 	UNUSED(op_ext);
diff --git a/FDTD/operator_extension.h b/FDTD/operator_extension.h
index cbe4b26..bc0b688 100644
--- a/FDTD/operator_extension.h
+++ b/FDTD/operator_extension.h
@@ -36,6 +36,8 @@ class Operator_Extension
 {
 	friend class Engine_Extension;
 public:
+	virtual ~Operator_Extension();
+
 	//! Create a clone of this extension, will return NULL if this is impossible
 	/*!
 		Create a clone of this extension, will return NULL if this is impossible (e.g. derived extension has no clone method and copy-constructor)...