diff --git a/include/boost/move/detail/placement_new.hpp b/include/boost/move/detail/placement_new.hpp
index 69d3332..11a9fca 100644
--- a/include/boost/move/detail/placement_new.hpp
+++ b/include/boost/move/detail/placement_new.hpp
@@ -18,6 +18,8 @@
 #  pragma once
 #endif
 
+#include <cstddef>
+
 struct boost_move_new_t{};
 
 //avoid including <new>