diff --git a/include/boost/detail/call_traits.hpp b/include/boost/detail/call_traits.hpp
index ee9d36c..a2c2ba3 100644
--- a/include/boost/detail/call_traits.hpp
+++ b/include/boost/detail/call_traits.hpp
@@ -21,6 +21,7 @@
 #ifndef BOOST_CONFIG_HPP
 #include <boost/config.hpp>
 #endif
+#include <cstddef>
 
 #include <boost/type_traits/is_arithmetic.hpp>
 #include <boost/type_traits/is_pointer.hpp>