add check is MSVC version >= vc++ 3.0
@@ -111,7 +111,7 @@ typedef long double realtype;
#if __STDC_VERSION__ >= 199901L
typedef int64_t sunindextype;
-#elif _MSC_VER
+#elif _MSC_VER >= 300
typedef __int64 sunindextype;
#else
typedef long int sunindextype;
