diff --git a/include/mapnik/expression_grammar_x3_config.hpp b/include/mapnik/expression_grammar_x3_config.hpp
index ffd9f9a1d..8aba3d75b 100644
--- a/include/mapnik/expression_grammar_x3_config.hpp
+++ b/include/mapnik/expression_grammar_x3_config.hpp
@@ -35,7 +35,7 @@ using phrase_context_type = x3::phrase_parse_context<x3::ascii::space_type>::typ
 
 // define combined context
 using context_type = x3::context<transcoder_tag,
-                                 std::reference_wrapper<mapnik::transcoder const> const,
+                                 std::reference_wrapper<mapnik::transcoder const>,
                                  phrase_context_type>;
 
 }}
diff --git a/include/mapnik/json/extract_bounding_boxes_x3_config.hpp b/include/mapnik/json/extract_bounding_boxes_x3_config.hpp
index 082e7b19a..54a2b17a4 100644
--- a/include/mapnik/json/extract_bounding_boxes_x3_config.hpp
+++ b/include/mapnik/json/extract_bounding_boxes_x3_config.hpp
@@ -84,30 +84,27 @@ using space_type = x3::standard::space_type;
 
 using phrase_parse_context_type = x3::phrase_parse_context<space_type>::type;
 
-using context_type = x3::context<keys_tag, std::reference_wrapper<keys_map> const,
-                                 phrase_parse_context_type>;
-
 using extract_bounding_boxes_context_type =
-    x3::context<bracket_tag, std::reference_wrapper<std::size_t> const,
-                     x3::context<feature_callback_tag, std::reference_wrapper<callback_type> const,
-                                      context_type>>;
+    x3::context<bracket_tag, std::reference_wrapper<std::size_t>,
+                x3::context<feature_callback_tag, std::reference_wrapper<callback_type>,
+                            context_type>>;
 
 using extract_bounding_boxes_reverse_context_type =
-    x3::context<keys_tag, std::reference_wrapper<keys_map> const,
-                x3::context<feature_callback_tag, std::reference_wrapper<callback_type> const,
-                            x3::context<bracket_tag, std::reference_wrapper<std::size_t> const,
+    x3::context<keys_tag, std::reference_wrapper<keys_map>,
+                x3::context<feature_callback_tag, std::reference_wrapper<callback_type>,
+                            x3::context<bracket_tag, std::reference_wrapper<std::size_t>,
                                         phrase_parse_context_type>>>;
 
 
 using extract_bounding_boxes_context_type_f =
-    x3::context<bracket_tag, std::reference_wrapper<std::size_t> const,
-                x3::context<feature_callback_tag, std::reference_wrapper<callback_type_f> const,
+    x3::context<bracket_tag, std::reference_wrapper<std::size_t>,
+                x3::context<feature_callback_tag, std::reference_wrapper<callback_type_f>,
                             context_type>>;
 
 using extract_bounding_boxes_reverse_context_type_f =
-    x3::context<keys_tag, std::reference_wrapper<keys_map> const,
-                x3::context<feature_callback_tag, std::reference_wrapper<callback_type_f> const,
-                            x3::context<bracket_tag, std::reference_wrapper<std::size_t> const,
+    x3::context<keys_tag, std::reference_wrapper<keys_map>,
+                x3::context<feature_callback_tag, std::reference_wrapper<callback_type_f>,
+                            x3::context<bracket_tag, std::reference_wrapper<std::size_t>,
                                         phrase_parse_context_type>>>;
 
 }}}
diff --git a/include/mapnik/json/json_grammar_config.hpp b/include/mapnik/json/json_grammar_config.hpp
index 854a50b21..e17b4773d 100644
--- a/include/mapnik/json/json_grammar_config.hpp
+++ b/include/mapnik/json/json_grammar_config.hpp
@@ -92,20 +92,20 @@ using iterator_type = char const*;
 
 using phrase_parse_context_type = x3::phrase_parse_context<space_type>::type;
 using context_type = x3::context<keys_tag,
-                                 std::reference_wrapper<keys_map> const,
+                                 std::reference_wrapper<keys_map>,
                                  phrase_parse_context_type>;
 
 using feature_context_type = x3::context<transcoder_tag,
-                                         std::reference_wrapper<mapnik::transcoder> const,
+                                         std::reference_wrapper<mapnik::transcoder>,
                                          x3::context<feature_tag,
-                                                          std::reference_wrapper<mapnik::feature_impl> const,
+                                                          std::reference_wrapper<mapnik::feature_impl>,
                                                           phrase_parse_context_type>>;
 
 // our spirit x3 grammars needs this one with changed order of feature_impl and transcoder (??)
 using feature_context_const_type = x3::context<feature_tag,
-                                               std::reference_wrapper<mapnik::feature_impl> const,
+                                               std::reference_wrapper<mapnik::feature_impl>,
                                                x3::context<transcoder_tag,
-                                                           std::reference_wrapper<mapnik::transcoder const> const,
+                                                           std::reference_wrapper<mapnik::transcoder const>,
                                                            phrase_parse_context_type>>;
 
 // helper macro
diff --git a/include/mapnik/svg/svg_grammar_config_x3.hpp b/include/mapnik/svg/svg_grammar_config_x3.hpp
index db1c7eb8d..63cbf79e1 100644
--- a/include/mapnik/svg/svg_grammar_config_x3.hpp
+++ b/include/mapnik/svg/svg_grammar_config_x3.hpp
@@ -40,8 +40,8 @@ using space_type = x3::standard::space_type;
 using iterator_type = char const*;
 
 using phrase_parse_context_type = x3::phrase_parse_context<space_type>::type;
-using svg_parse_context_type = x3::context<relative_tag, std::reference_wrapper<bool> const,
-                                           x3::context<svg_path_tag,std::reference_wrapper<svg_converter_type> const,
+using svg_parse_context_type = x3::context<relative_tag, std::reference_wrapper<bool>,
+                                           x3::context<svg_path_tag,std::reference_wrapper<svg_converter_type>,
                                                        phrase_parse_context_type>>;
 
 inline double deg2rad(double deg) {return (M_PI * deg) / 180.0;}
diff --git a/src/css_color_grammar_x3.cpp b/src/css_color_grammar_x3.cpp
index 372f0dff0..5a7a6ed2c 100644
--- a/src/css_color_grammar_x3.cpp
+++ b/src/css_color_grammar_x3.cpp
@@ -21,7 +21,7 @@
  *****************************************************************************/
 
 #include <mapnik/css_color_grammar_x3_def.hpp>
-
+#include <mapnik/image_filter_types.hpp>
 namespace mapnik { namespace css_color_grammar {
 
 namespace x3 = boost::spirit::x3;
@@ -30,4 +30,7 @@ using context_type = x3::phrase_parse_context<x3::ascii::space_type>::type;
 
 BOOST_SPIRIT_INSTANTIATE(css_color_grammar_type, iterator_type, context_type);
 
+template bool parse_rule<iterator_type, context_type, mapnik::filter::color_to_alpha>
+(css_color_grammar_type, iterator_type&, iterator_type const&, context_type const&, mapnik::filter::color_to_alpha&);
+
 }}