diff --git a/include/mapnik/util/timer.hpp b/include/mapnik/util/timer.hpp
index 7541a584f..c51962474 100644
--- a/include/mapnik/util/timer.hpp
+++ b/include/mapnik/util/timer.hpp
@@ -25,6 +25,7 @@
 
 #include <string>
 #include <chrono>
+#include <ostream>
 
 namespace mapnik {
 
diff --git a/include/mapnik/util/variant_io.hpp b/include/mapnik/util/variant_io.hpp
index 220d8893b..cb5abb37b 100644
--- a/include/mapnik/util/variant_io.hpp
+++ b/include/mapnik/util/variant_io.hpp
@@ -23,6 +23,8 @@
 #ifndef MAPNIK_UTIL_VARIANT_IO_HPP
 #define MAPNIK_UTIL_VARIANT_IO_HPP
 
+#include <ostream>
+#include <mapbox/variant.hpp>
 
 namespace mapbox { namespace util {