diff --git a/include/mapnik/value.hpp b/include/mapnik/value.hpp
index a7b900f9d..cb72592e8 100644
--- a/include/mapnik/value.hpp
+++ b/include/mapnik/value.hpp
@@ -47,6 +47,15 @@
 #include <unicode/unistr.h>
 #include <unicode/ustring.h>
 
+namespace boost {
+
+  template <>
+  struct has_nothrow_copy<mapnik::value_unicode_string>
+    : mpl::true_
+  {
+  };
+
+}
 
 namespace mapnik  {