diff --git a/src/expression_string.cpp b/src/expression_string.cpp
index 2558b863a..f42d5f6cc 100644
--- a/src/expression_string.cpp
+++ b/src/expression_string.cpp
@@ -21,15 +21,22 @@
  *****************************************************************************/
 
 // mapnik
+
+#include <mapnik/config.hpp> // needed by msvc
+#include <mapnik/expression_string.hpp> // needed by msvc
+#include <mapnik/expression_node_types.hpp>
 #include <mapnik/expression_node.hpp>
 #include <mapnik/attribute.hpp>
 #include <mapnik/value.hpp>
 
 // boost
 #include <boost/variant.hpp>
+#if defined(BOOST_REGEX_HAS_ICU)
+#include <boost/regex/icu.hpp>          // for u32regex
+#endif
 
 // icu
-#include <unicode/uversion.h>
+#include <unicode/unistr.h>             // for UnicodeString
 
 
 namespace mapnik