diff --git a/include/boost/python/register_ptr_to_python.hpp b/include/boost/python/register_ptr_to_python.hpp
index 0842e1c1..cbd42cc1 100644
--- a/include/boost/python/register_ptr_to_python.hpp
+++ b/include/boost/python/register_ptr_to_python.hpp
@@ -8,11 +8,12 @@
 
 #include <boost/python/pointee.hpp>
 #include <boost/python/object.hpp>
+#include <boost/python/object/class_wrapper.hpp>
 
 namespace boost { namespace python {
     
 template <class P>
-void register_ptr_to_python(P* = 0)
+void register_ptr_to_python(BOOST_EXPLICIT_TEMPLATE_TYPE(P))
 {
     typedef typename boost::python::pointee<P>::type X;
     objects::class_value_wrapper<