diff --git a/dtool/src/parser-inc/winsock2.h b/dtool/src/parser-inc/winsock2.h
index 06df48e2cd..474a821987 100644
--- a/dtool/src/parser-inc/winsock2.h
+++ b/dtool/src/parser-inc/winsock2.h
@@ -1,3 +1,6 @@
+#ifndef _WINSOCK2API_
+#define _WINSOCK2API_
+#define _WINSOCKAPI_   /* Prevent inclusion of winsock.h in windows.h */
 
 typedef int SOCKET ;
 
@@ -11,3 +14,4 @@ typedef struct fd_set {
         SOCKET  fd_array[10];   /* an array of SOCKETs */
 } fd_set;
 
+#endif