diff --git a/Source/RMG-Core/String.hpp b/Source/RMG-Core/String.hpp
index e50c16d5..d5235eea 100644
--- a/Source/RMG-Core/String.hpp
+++ b/Source/RMG-Core/String.hpp
@@ -10,6 +10,7 @@
 #ifndef CORE_STRING_HPP
 #define CORE_STRING_HPP
 
+#include <cstdint>
 #include <string>
 
 // returns lowercase string