diff --git a/src/network_asio.hpp b/src/network_asio.hpp
index 6686e357ddf..854844d4222 100644
--- a/src/network_asio.hpp
+++ b/src/network_asio.hpp
@@ -16,7 +16,7 @@
 
 #ifdef _WIN32
 
-#if _WIN32_WINNT == _WIN32_WINNT_WINXP
+#if _WIN32_WINNT < _WIN32_WINNT_VISTA
 #define BOOST_ASIO_DISABLE_IOCP
 #endif
 
diff --git a/src/wesnothd_connection.hpp b/src/wesnothd_connection.hpp
index bddd5720a45..cf6d7bcb066 100644
--- a/src/wesnothd_connection.hpp
+++ b/src/wesnothd_connection.hpp
@@ -20,7 +20,7 @@
 // gethostbyname in socket_ops.ipp. This define silences that.
 #define _WINSOCK_DEPRECATED_NO_WARNINGS
 
-#if _WIN32_WINNT == _WIN32_WINNT_WINXP
+#if _WIN32_WINNT < _WIN32_WINNT_VISTA
 #define BOOST_ASIO_DISABLE_IOCP
 #endif