diff --git a/include/mapbox/eternal.hpp b/include/mapbox/eternal.hpp
index 10c2f82..ab92ccb 100644
--- a/include/mapbox/eternal.hpp
+++ b/include/mapbox/eternal.hpp
@@ -2,6 +2,7 @@
 
 #include <utility>
 #include <functional>
+#include <cstdint>
 
 // GCC 4.9 compatibility
 #if !defined(__clang__) && defined(__GNUC__) && __GNUC__ < 5