diff --git a/include/boost/config/platform/cygwin.hpp b/include/boost/config/platform/cygwin.hpp
index 97e29053..6e77bb5b 100644
--- a/include/boost/config/platform/cygwin.hpp
+++ b/include/boost/config/platform/cygwin.hpp
@@ -24,7 +24,9 @@
 #  define BOOST_HAS_GETTIMEOFDAY
 #  define BOOST_HAS_PTHREAD_MUTEXATTR_SETTYPE
 #else
-#  define BOOST_HAS_WINTHREADS
+#  if !defined(BOOST_HAS_WINTHREADS)
+#     define BOOST_HAS_WINTHREADS
+#  endif
 #  define BOOST_HAS_FTIME
 #endif
 
@@ -32,3 +34,4 @@
 #include <boost/config/posix_features.hpp>
  
 
+