--- a/include/mapnik/unicode.hpp	2017-10-31 17:53:23.507237672 +0100
+++ b/include/mapnik/unicode.hpp	2017-10-31 17:53:47.096237053 +0100
@@ -31,6 +31,8 @@
 // std
 #include <cstdint>
 #include <string>
+// icu
+#include <unicode/unistr.h>
 
 struct UConverter;