diff --git a/include/boost/leaf/detail/optional.hpp b/include/boost/leaf/detail/optional.hpp
index 1cf8973..afdfd85 100644
--- a/include/boost/leaf/detail/optional.hpp
+++ b/include/boost/leaf/detail/optional.hpp
@@ -7,6 +7,7 @@
 #ifndef UUID_47258FCCB6B411E8A1F35AA00C39171A
 #define UUID_47258FCCB6B411E8A1F35AA00C39171A
 
+#include <utility>
 #include <new>
 #include <assert.h>