diff --git a/src/svg/svg_parser.cpp b/src/svg/svg_parser.cpp
index 9247eef86..0d4db78d4 100644
--- a/src/svg/svg_parser.cpp
+++ b/src/svg/svg_parser.cpp
@@ -94,29 +94,26 @@ void parse_attr(svg_parser & parser,rapidxml::xml_node<char> const* node);
 void parse_attr(svg_parser & parser,char const * name, char const* value);
 
 
-namespace grammar {
+namespace { namespace grammar {
 
 namespace x3 = boost::spirit::x3;
 
 using color_lookup_type = std::vector<std::pair<double, agg::rgba8> >;
 using pairs_type = std::vector<std::pair<std::string, std::string> >;
 
-x3::rule<class key_value_sequence_ordered, pairs_type> const key_value_sequence_ordered("key_value_sequence_ordered");
-x3::rule<class key_value, std::pair<std::string, std::string> > key_value("key_value");
-x3::rule<class key, std::string> key("key");
-x3::rule<class value_, std::string> value("value");
+x3::rule<class key_value_sequence_ordered_tag, pairs_type> const key_value_sequence_ordered("key_value_sequence_ordered");
+x3::rule<class key_value_tag, std::pair<std::string, std::string> > key_value("key_value");
+x3::rule<class key_tag, std::string> key("key");
+x3::rule<class value_tag, std::string> value("value");
 
 auto const key_def = x3::char_("a-zA-Z_") > *x3::char_("a-zA-Z_0-9-");
 auto const value_def = +(x3::char_ - ';');
 auto const key_value_def = key > -(':' > value);
 auto const key_value_sequence_ordered_def = key_value % ';';
 
-BOOST_SPIRIT_DEFINE(key);
-BOOST_SPIRIT_DEFINE(value);
-BOOST_SPIRIT_DEFINE(key_value);
-BOOST_SPIRIT_DEFINE(key_value_sequence_ordered);
+BOOST_SPIRIT_DEFINE(key, value, key_value, key_value_sequence_ordered);
 
-}
+}}
 
 template <typename T>
 mapnik::color parse_color(T & error_messages, const char* str)