diff --git a/include/mapnik/image_filter_grammar.hpp b/include/mapnik/image_filter_grammar.hpp
index ef78b4e34..d98ad0e82 100644
--- a/include/mapnik/image_filter_grammar.hpp
+++ b/include/mapnik/image_filter_grammar.hpp
@@ -43,9 +43,9 @@ struct image_filter_grammar :
     qi::rule<Iterator, ContType(), qi::ascii::space_type> start;
     qi::rule<Iterator, ContType(), qi::ascii::space_type> filter;
     qi::rule<Iterator, qi::locals<int,int>, void(ContType&), qi::ascii::space_type> agg_blur_filter;
-    qi::rule<Iterator, qi::locals<std::string>, void(ContType&), qi::ascii::space_type> hsla_filter;
+    qi::rule<Iterator, qi::locals<double,double,double,double,double,double,double,double>,
+             void(ContType&), qi::ascii::space_type> hsla_filter;
     qi::rule<Iterator, qi::locals<mapnik::color,mapnik::color>, void(ContType&), qi::ascii::space_type> colorize_alpha_filter;
-    qi::rule<Iterator, std::string(char), qi::ascii::space_type> string_arg;
     qi::rule<Iterator, qi::ascii::space_type> no_args;
     qi::uint_parser< unsigned, 10, 1, 3 > radius_;
     css_color_grammar<Iterator> css_color_;
diff --git a/include/mapnik/image_filter_types.hpp b/include/mapnik/image_filter_types.hpp
index 276caac2a..72075f2ec 100644
--- a/include/mapnik/image_filter_types.hpp
+++ b/include/mapnik/image_filter_types.hpp
@@ -27,8 +27,8 @@
 #include <mapnik/config.hpp>
 #include <mapnik/color.hpp>
 // boost
+#include <boost/variant.hpp>
 #include <boost/variant/variant_fwd.hpp>
-
 // stl
 #include <vector>
 #include <ostream>
@@ -56,18 +56,20 @@ struct agg_stack_blur
 
 struct hsla
 {
-    hsla(std::string const& tint_string)
-        : tinter(tint_string) {}
-    std::string tinter;
+    hsla(double h0, double h1,
+         double s0, double s1,
+         double l0, double l1,
+         double a0, double a1)
+    {
+        // TODO: implement me!
+    }
 };
 
-
-
 struct colorize_alpha
 {
     colorize_alpha(mapnik::color const& c0, mapnik::color const& c1)
     {
-        //do work
+         // TODO: implement me!
     }
 };
 
@@ -104,7 +106,7 @@ inline std::ostream& operator<< (std::ostream& os, agg_stack_blur const& filter)
 
 inline std::ostream& operator<< (std::ostream& os, hsla const& filter)
 {
-    os << "hsla(" << filter.tinter << ')';
+    os << "hsla(" << "TODO" << ')';
     return os;
 }
 
diff --git a/src/image_filter_grammar.cpp b/src/image_filter_grammar.cpp
index fba6f213f..28163ad91 100644
--- a/src/image_filter_grammar.cpp
+++ b/src/image_filter_grammar.cpp
@@ -44,10 +44,17 @@ image_filter_grammar<Iterator,ContType>::image_filter_grammar()
     using qi::_1;
     using qi::_a;
     using qi::_b;
+    using qi::_c;
+    using qi::_d;
+    using qi::_e;
+    using qi::_f;
+    using qi::_g;
+    using qi::_h;
     using qi::_r1;
     using qi::eps;
     using qi::char_;
     using qi::lexeme;
+    using qi::double_;
     using boost::spirit::ascii::string;
     using phoenix::push_back;
     using phoenix::construct;
@@ -94,8 +101,13 @@ image_filter_grammar<Iterator,ContType>::image_filter_grammar()
         [push_back(_r1,construct<mapnik::filter::agg_stack_blur>(_a,_b))]
         ;
 
-    hsla_filter = lit("hsla") >> lit('(') >> string_arg(')')[_a = _1] >> lit(')')
-        [push_back(_r1,construct<mapnik::filter::hsla>(_a))]
+    hsla_filter = lit("hsla")
+        >> lit('(')
+        >> double_[_a = _1] >> lit('x') >> double_[_b = _1] >> lit(';')
+        >> double_[_c = _1] >> lit('x') >> double_[_d = _1] >> lit(';')
+        >> double_[_e = _1] >> lit('x') >> double_[_f = _1] >> lit(';')
+        >> double_[_g = _1] >> lit('x') >> double_[_h = _1] >> lit(')')
+        [push_back(_r1, construct<mapnik::filter::hsla>(_a,_b,_c,_d,_e,_f,_g,_h))]
         ;
 
     colorize_alpha_filter = lit("colorize-alpha")
@@ -105,7 +117,6 @@ image_filter_grammar<Iterator,ContType>::image_filter_grammar()
         [push_back(_r1,construct<mapnik::filter::colorize_alpha>(_a,_b))]
         ;
 
-    string_arg = + (char_ - lit(_r1));
     no_args = -(lit('(') >> lit(')'));
 }