diff --git a/src/ripple/protocol/impl/BuildInfo.cpp b/src/ripple/protocol/impl/BuildInfo.cpp
index 25a994aeb..11d34b2ad 100644
--- a/src/ripple/protocol/impl/BuildInfo.cpp
+++ b/src/ripple/protocol/impl/BuildInfo.cpp
@@ -23,6 +23,7 @@
 #include <ripple/protocol/BuildInfo.h>
 #include <boost/preprocessor/stringize.hpp>
 #include <algorithm>
+#include <optional>
 
 namespace ripple {