diff --git a/include/boost/type_traits/composite_traits.hpp b/include/boost/type_traits/composite_traits.hpp
index fd7b62d..359d1b8 100644
--- a/include/boost/type_traits/composite_traits.hpp
+++ b/include/boost/type_traits/composite_traits.hpp
@@ -20,6 +20,8 @@
 #ifndef COMPOSITE_TYPE_TRAITS_HPP
 #define COMPOSITE_TYPE_TRAITS_HPP
 
+#include <cstddef>
+
 #ifndef BOOST_ICE_TYPE_TRAITS_HPP
 #include <boost/type_traits/ice.hpp>
 #endif