diff --git a/library/net_sockets.c b/library/net_sockets.c
index dbde510..5c1e665 100644
--- a/library/net_sockets.c
+++ b/library/net_sockets.c
@@ -54,8 +54,7 @@
 
 #define IS_EINTR( ret ) ( ( ret ) == WSAEINTR )
 
-#if !defined(_WIN32_WINNT) || (_WIN32_WINNT < 0x0501)
-#undef _WIN32_WINNT
+#if !defined(_WIN32_WINNT)
 /* Enables getaddrinfo() & Co */
 #define _WIN32_WINNT 0x0501
 #endif
@@ -64,6 +63,9 @@
 
 #include <winsock2.h>
 #include <windows.h>
+#if (_WIN32_WINNT < 0x0501)
+#include <wspiapi.h>
+#endif
 
 #if defined(_MSC_VER)
 #if defined(_WIN32_WCE)