diff --git a/include/boost/utility/addressof.hpp b/include/boost/utility/addressof.hpp
index ac42a51..95cd92f 100644
--- a/include/boost/utility/addressof.hpp
+++ b/include/boost/utility/addressof.hpp
@@ -27,6 +27,9 @@ template<class T> struct addr_impl_ref
 
     inline addr_impl_ref( T & v ): v_( v ) {}
     inline operator T& () const { return v_; }
+
+private:
+    addr_impl_ref & operator=(const addr_impl_ref &);
 };
 
 template<class T> struct addressof_impl