diff --git a/include/mapnik/hash_variant.hpp b/include/mapnik/hash_variant.hpp
new file mode 100644
index 000000000..2e6a866cd
--- /dev/null
+++ b/include/mapnik/hash_variant.hpp
@@ -0,0 +1,48 @@
+//-----------------------------------------------------------------------------
+// boost variant/detail/hash_variant.hpp header file
+// See http://www.boost.org for updates, documentation, and revision history.
+//-----------------------------------------------------------------------------
+//
+// Copyright (c) 2011
+// Antony Polukhin
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// TODO: Remove this file once the minimum Boost version is bumped to 1.50
+
+#ifndef BOOST_HASH_VARIANT_FUNCTION_HPP
+#define BOOST_HASH_VARIANT_FUNCTION_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+#include <boost/variant/variant_fwd.hpp>
+#include <boost/variant/static_visitor.hpp>
+#include <boost/variant/apply_visitor.hpp>
+#include <boost/functional/hash_fwd.hpp>
+
+namespace boost {
+
+    namespace detail { namespace variant {
+        struct variant_hasher: public boost::static_visitor<std::size_t> {
+            template <class T>
+            std::size_t operator()(T const& val) const {
+                using namespace boost;
+                hash<T> hasher;
+                return hasher(val);
+            }
+        };
+    }}
+
+    template < BOOST_VARIANT_ENUM_PARAMS(typename T) >
+    std::size_t hash_value(variant< BOOST_VARIANT_ENUM_PARAMS(T) > const& val) {
+        std::size_t seed = boost::apply_visitor(detail::variant::variant_hasher(), val);
+        hash_combine(seed, val.which());
+        return seed;
+    }
+}
+
+#endif
diff --git a/include/mapnik/unicode.hpp b/include/mapnik/unicode.hpp
index 0de34ac98..fd4e8e40a 100644
--- a/include/mapnik/unicode.hpp
+++ b/include/mapnik/unicode.hpp
@@ -51,7 +51,7 @@ private:
 };
 }
 
-namespace icu_50 {
+namespace U_ICU_NAMESPACE {
 inline std::size_t hash_value(const UnicodeString& val) {
     return val.hashCode();
 }
diff --git a/include/mapnik/value.hpp b/include/mapnik/value.hpp
index 40f329f33..4c51f4374 100644
--- a/include/mapnik/value.hpp
+++ b/include/mapnik/value.hpp
@@ -37,6 +37,7 @@
 #include <boost/scoped_array.hpp>
 #include <boost/concept_check.hpp>
 #include <boost/functional/hash.hpp>
+#include "hash_variant.hpp"
 
 // stl
 #include <iostream>