diff --git a/include/boost/stacktrace/safe_dump_to.hpp b/include/boost/stacktrace/safe_dump_to.hpp
index 7f63913..b630905 100644
--- a/include/boost/stacktrace/safe_dump_to.hpp
+++ b/include/boost/stacktrace/safe_dump_to.hpp
@@ -12,6 +12,8 @@
 #   pragma once
 #endif
 
+#include <cstddef>
+
 #if defined(BOOST_WINDOWS)
 #include <boost/winapi/config.hpp>
 #endif