diff --git a/include/boost/python/converter/builtin_converters.hpp b/include/boost/python/converter/builtin_converters.hpp
index 4db0eb9c..c0d2ba09 100644
--- a/include/boost/python/converter/builtin_converters.hpp
+++ b/include/boost/python/converter/builtin_converters.hpp
@@ -27,9 +27,13 @@ namespace detail
 namespace converter
 {
   template <class T> struct callback_to_python;
+  BOOST_PYTHON_DECL PyObject* do_call_to_python(char);
+  BOOST_PYTHON_DECL PyObject* do_call_to_python(char const*);
+  BOOST_PYTHON_DECL PyObject* do_call_to_python(PyObject*);
+  BOOST_PYTHON_DECL PyObject* do_callback_to_python(PyObject*);
 }
 
-# define BOOST_PYTHON_TO_PYTHON_BY_VALUE(T, expr)   \
+# define BOOST_PYTHON_CALL_TO_PYTHON_BY_VALUE(T, expr)   \
     template <> struct to_python_value<T&>          \
         : detail::builtin_to_python                 \
     {                                               \
@@ -45,7 +49,9 @@ namespace converter
         {                                           \
             return (expr);                          \
         }                                           \
-    };                                              \
+    };
+
+# define BOOST_PYTHON_CALLBACK_TO_PYTHON_BY_VALUE(T, expr)   \
     namespace converter                             \
     {                                               \
       template <> struct callback_to_python< T >    \
@@ -57,8 +63,11 @@ namespace converter
        private:                                     \
           ref m_held;                               \
       };                                            \
-    }                                               
+    } 
 
+# define BOOST_PYTHON_TO_PYTHON_BY_VALUE(T, expr)   \
+        BOOST_PYTHON_CALL_TO_PYTHON_BY_VALUE(T,expr) \
+        BOOST_PYTHON_CALLBACK_TO_PYTHON_BY_VALUE(T,expr)
 
 # define BOOST_PYTHON_TO_INT(T)                                         \
     BOOST_PYTHON_TO_PYTHON_BY_VALUE(signed T, PyInt_FromLong(x))        \
@@ -71,12 +80,14 @@ BOOST_PYTHON_TO_INT(int)
 BOOST_PYTHON_TO_INT(long)
 # undef BOOST_TO_PYTHON_INT
 
-BOOST_PYTHON_TO_PYTHON_BY_VALUE(char const*, x ? PyString_FromString(x) : boost::python::detail::none())
+BOOST_PYTHON_TO_PYTHON_BY_VALUE(char, converter::do_call_to_python(x))
+BOOST_PYTHON_TO_PYTHON_BY_VALUE(char const*, converter::do_call_to_python(x))
 BOOST_PYTHON_TO_PYTHON_BY_VALUE(std::string, PyString_FromString(x.c_str()))
 BOOST_PYTHON_TO_PYTHON_BY_VALUE(float, PyFloat_FromDouble(x))
 BOOST_PYTHON_TO_PYTHON_BY_VALUE(double, PyFloat_FromDouble(x))
 BOOST_PYTHON_TO_PYTHON_BY_VALUE(long double, PyFloat_FromDouble(x))
-BOOST_PYTHON_TO_PYTHON_BY_VALUE(PyObject*, (x ? x : boost::python::detail::none()))
+BOOST_PYTHON_CALL_TO_PYTHON_BY_VALUE(PyObject*, converter::do_call_to_python(x))
+BOOST_PYTHON_CALLBACK_TO_PYTHON_BY_VALUE(PyObject*, converter::do_callback_to_python(x))
 BOOST_PYTHON_TO_PYTHON_BY_VALUE(std::complex<float>, PyComplex_FromDoubles(x.real(), x.imag()))
 BOOST_PYTHON_TO_PYTHON_BY_VALUE(std::complex<double>, PyComplex_FromDoubles(x.real(), x.imag()))
 BOOST_PYTHON_TO_PYTHON_BY_VALUE(std::complex<long double>, PyComplex_FromDoubles(x.real(), x.imag()))