diff -urEbwB mingw-w64-headers-1.0b.20100730/include/mswsock.h mingw-w64-headers-1.0b.20100730/include/mswsock.h
--- mingw-w64-headers-1.0b.20100730/include/mswsock.h	2010-05-26 19:21:09.000000000 +0200
+++ mingw-w64-headers-1.0b.20100730/include/mswsock.h	2010-08-11 05:57:39.000000000 +0200
@@ -6,6 +6,8 @@
 #ifndef _MSWSOCK_
 #define _MSWSOCK_
 
+#include <winsock2.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif