diff --git a/include/boost/detail/utf8_codecvt_facet.hpp b/include/boost/detail/utf8_codecvt_facet.hpp
index ac7e7bf..a8bedc2 100644
--- a/include/boost/detail/utf8_codecvt_facet.hpp
+++ b/include/boost/detail/utf8_codecvt_facet.hpp
@@ -79,10 +79,8 @@
 // specialized on those types for this to work.
 
 #include <locale>
-// for mbstate_t
-#include <wchar.h>
-// for std::size_t
-#include <cstddef>
+#include <cwchar>  // for mbstate_t
+#include <cstddef> // for std::size_t
 
 #include <boost/config.hpp>
 #include <boost/detail/workaround.hpp>