diff --git a/Include/RmlUi/Core/Types.h b/Include/RmlUi/Core/Types.h
index c3997377a..4661b7a65 100644
--- a/Include/RmlUi/Core/Types.h
+++ b/Include/RmlUi/Core/Types.h
@@ -31,6 +31,7 @@
 
 #include "../Config/Config.h"
 
+#include <cstdint>
 #include <cstdlib>
 #include <memory>