diff --git a/boost/yap/detail/expression.hpp b/boost/yap/detail/expression.hpp
index 48159eb..021d008 100644
--- a/boost/yap/detail/expression.hpp
+++ b/boost/yap/detail/expression.hpp
@@ -6,6 +6,7 @@
 #include <boost/hana/tuple.hpp>
 #include <boost/hana/size.hpp>
 
+#include <memory>
 #include <type_traits>