diff --git a/include/boost/detail/interlocked.hpp b/include/boost/detail/interlocked.hpp
index 258320c..b6c8d75 100644
--- a/include/boost/detail/interlocked.hpp
+++ b/include/boost/detail/interlocked.hpp
@@ -92,7 +92,7 @@ extern "C" void* __cdecl _InterlockedExchangePointer( void* volatile *, void* );
 # define BOOST_INTERLOCKED_EXCHANGE _InterlockedExchange
 # define BOOST_INTERLOCKED_EXCHANGE_ADD _InterlockedExchangeAdd
 
-#elif defined( WIN32 ) || defined( _WIN32 ) || defined( __WIN32__ )
+#elif defined( WIN32 ) || defined( _WIN32 ) || defined( __WIN32__ ) || defined( __CYGWIN__ )
 
 namespace boost
 {