diff --git a/src/ripple/protocol/TxFlags.h b/src/ripple/protocol/TxFlags.h
index 0161ca99a..3791c47dd 100644
--- a/src/ripple/protocol/TxFlags.h
+++ b/src/ripple/protocol/TxFlags.h
@@ -20,6 +20,8 @@
 #ifndef RIPPLE_PROTOCOL_TXFLAGS_H_INCLUDED
 #define RIPPLE_PROTOCOL_TXFLAGS_H_INCLUDED
 
+#include <cstdint>
+
 namespace ripple {
 
 //