diff --git a/src/xpdev/gen_defs.h b/src/xpdev/gen_defs.h
index b42e3412b49010e706da9e76af1d95ea55caeb1d..bff0dc1ba39e6c1c026a88a6ea16fc2576c5160d 100644
--- a/src/xpdev/gen_defs.h
+++ b/src/xpdev/gen_defs.h
@@ -199,7 +199,7 @@ typedef ulong   uint32_t;
 
 #endif
 
-#if !defined(__MSDOS__)
+#if !defined(_MSDOS)
 #if defined(_MSC_VER) || defined(__WATCOMC__) || defined(__BORLANDC__)
 typedef SSIZE_T ssize_t;
 typedef signed __int64 int64_t;