Fix MingW version issue
diff --git a/library/net.c b/library/net.c
index e666fad..fd5fd12 100644
--- a/library/net.c
+++ b/library/net.c
@@ -32,13 +32,14 @@
 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
     !defined(EFI32)
 
-#include <winsock2.h>
-#include <windows.h>
-
 #if defined(POLARSSL_HAVE_IPV6)
+#define _WIN32_WINNT 0x0501
 #include <ws2tcpip.h>
 #endif
 
+#include <winsock2.h>
+#include <windows.h>
+
 #if defined(_WIN32_WCE)
 #pragma comment( lib, "ws2.lib" )
 #else