Anonymous namespaces and friend functions

I have the class declared like this in the header fiel:

//header
class MyClass
{
public:
	MyClass();
	MyClass(const MyClass&);
	MyClass& operator=(const MyClass&);
	~MyClass();

	friend int MyFriendFunc(const MyClass&);

private:
	int m_i ;
};


//source
namespace
{
	void MyFriendFunc(const MyClass& mc){ return mc.m_i++ ;}
}

//MyClass impl ...



I get compiltion errors (MyFriendFunc cannot  access private member of 
MyClass ...

using the ns resolution operator does not seem to work either:

friend int ::MyFriendFunc(const MyClass&);