diff --git a/include/boost/archive/iterators/wchar_from_mb.hpp b/include/boost/archive/iterators/wchar_from_mb.hpp
index 19e1120fc..294351b48 100644
--- a/include/boost/archive/iterators/wchar_from_mb.hpp
+++ b/include/boost/archive/iterators/wchar_from_mb.hpp
@@ -18,9 +18,7 @@
 
 #include <cctype>
 #include <cstddef> // size_t
-#ifndef BOOST_NO_CWCHAR
 #include <cwchar>  // mbstate_t
-#endif
 #include <algorithm> // copy
 
 #include <boost/config.hpp>