diff --git a/bindings/python/mapnik_projection.cpp b/bindings/python/mapnik_projection.cpp
index b15dcc444..3eebee26c 100644
--- a/bindings/python/mapnik_projection.cpp
+++ b/bindings/python/mapnik_projection.cpp
@@ -89,7 +89,7 @@ void export_projection ()
 {
     using namespace boost::python; 
 
-    class_<projection>("Projection", "Represents a map projection.",init<optional<std::string const&> >(
+    class_<projection>("Projection", "Represents a map projection.",init<std::string const&>(
                            (arg("proj4_string")),
                            "Constructs a new projection from its PROJ.4 string representation.\n"
                            "\n"