diff --git a/include/boost/smart_ptr/detail/lightweight_mutex.hpp b/include/boost/smart_ptr/detail/lightweight_mutex.hpp
index a2fc281..d46b193 100644
--- a/include/boost/smart_ptr/detail/lightweight_mutex.hpp
+++ b/include/boost/smart_ptr/detail/lightweight_mutex.hpp
@@ -32,7 +32,7 @@
 #  include <boost/smart_ptr/detail/lwm_nop.hpp>
 #elif defined(BOOST_HAS_PTHREADS)
 #  include <boost/smart_ptr/detail/lwm_pthreads.hpp>
-#elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
+#elif defined(BOOST_HAS_WINTHREADS) || defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__CYGWIN__)
 #  include <boost/smart_ptr/detail/lwm_win32_cs.hpp>
 #else
 // Use #define BOOST_DISABLE_THREADS to avoid the error