diff --git a/bindings/python/mapnik_python.cpp b/bindings/python/mapnik_python.cpp
index 5346f2c9b..70b361e75 100644
--- a/bindings/python/mapnik_python.cpp
+++ b/bindings/python/mapnik_python.cpp
@@ -83,24 +83,13 @@ void export_label_collision_detector();
 #include <mapnik/value_error.hpp>
 #include <mapnik/save_map.hpp>
 #include "python_grid_utils.hpp"
+#include "mapnik_value_converter.hpp"
 
 #if defined(HAVE_CAIRO) && defined(HAVE_PYCAIRO)
 #include <pycairo.h>
 static Pycairo_CAPI_t *Pycairo_CAPI;
 #endif
 
-
-namespace boost { namespace python {
-
-    struct mapnik_value_to_python
-    {
-        static PyObject* convert(mapnik::value const& v)
-        {
-            return boost::apply_visitor(value_converter(),v.base());
-        }
-    };
-    }}
-
 void render(const mapnik::Map& map,
             mapnik::image_32& image,
             double scale_factor = 1.0,
@@ -651,5 +640,6 @@ BOOST_PYTHON_MODULE(_mapnik)
 
     register_ptr_to_python<mapnik::expression_ptr>();
     register_ptr_to_python<mapnik::path_expression_ptr>();
+    to_python_converter<mapnik::value_holder,mapnik_param_to_python>();
     to_python_converter<mapnik::value,mapnik_value_to_python>();
 }
diff --git a/bindings/python/mapnik_value_converter.hpp b/bindings/python/mapnik_value_converter.hpp
index 292f84d14..bbac939b6 100644
--- a/bindings/python/mapnik_value_converter.hpp
+++ b/bindings/python/mapnik_value_converter.hpp
@@ -27,6 +27,7 @@
 #include <boost/implicit_cast.hpp>
 
 namespace boost { namespace python {
+
     struct value_converter : public boost::static_visitor<PyObject*>
     {
         PyObject * operator() (int val) const
@@ -48,6 +49,13 @@ namespace boost { namespace python {
             return ::PyBool_FromLong(val);
         }
 
+        PyObject * operator() (std::string const& s) const
+        {
+            PyObject *obj = Py_None;
+            obj = ::PyUnicode_DecodeUTF8(s.c_str(),implicit_cast<ssize_t>(s.length()),0);
+            return obj;
+        }
+
         PyObject * operator() (UnicodeString const& s) const
         {
             std::string buffer;
@@ -63,6 +71,25 @@ namespace boost { namespace python {
         }
     };
 
+
+    struct mapnik_value_to_python
+    {
+        static PyObject* convert(mapnik::value const& v)
+        {
+            return boost::apply_visitor(value_converter(),v.base());
+        }
+
+    };
+
+    struct mapnik_param_to_python
+    {
+        static PyObject* convert(mapnik::value_holder const& v)
+        {
+            return boost::apply_visitor(value_converter(),v);
+        }
+    };
+
+
     }
 }