diff --git a/lib/config-win32.h b/lib/config-win32.h
index 871e6bef6c98c54eb523a113a5dff535c26bf2cc..1090a1c25e5a14fd0d3ccb5720f8ce2a5c4a4ff6 100644
--- a/lib/config-win32.h
+++ b/lib/config-win32.h
@@ -290,11 +290,9 @@
 /* Define as the return type of signal handlers (int or void).  */
 /* #define RETSIGTYPE void */
 
-/* Define to `unsigned' if size_t is not an available 'typedefed' type */
-/* #define size_t unsigned */
-
-/* Define to 'int' if ssize_t is not an available 'typedefed' type */
 #if (defined(__WATCOMC__) && (__WATCOMC__ >= 1240)) || defined(__POCC__)
+#elif defined(_WIN64)
+#define ssize_t __int64
 #else
 #define ssize_t int
 #endif