diff --git a/lib/curl_setup.h b/lib/curl_setup.h
index ad83fec5f..e4d8721a0 100644
--- a/lib/curl_setup.h
+++ b/lib/curl_setup.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -694,4 +694,9 @@ int netware_init(void);
 #define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
 #endif
 
+/* Define S_ISDIR if not defined by system headers, f.e. MSVC */
+#if !defined(S_ISDIR) && defined(S_IFMT) && defined(S_IFDIR)
+#define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
+#endif
+
 #endif /* HEADER_CURL_SETUP_H */