diff --git a/include/mapnik/value_hash.hpp b/include/mapnik/value_hash.hpp
index da2621269..4c12bbe97 100644
--- a/include/mapnik/value_hash.hpp
+++ b/include/mapnik/value_hash.hpp
@@ -29,7 +29,6 @@
 
 // stl
 #include <functional>
-#include <cassert>
 
 // icu
 #include <unicode/unistr.h>