--- mstools/h/dos.h	2018/08/09 18:20:30	1.1.1.2
+++ mstools/h/dos.h	2018/08/09 18:21:09	1.1.1.3
@@ -18,14 +18,40 @@ extern "C" {
 #endif
 
 
-#ifndef MIPS
-#if (_MSC_VER <= 600)
-#define __cdecl _cdecl
-#endif
+/*
+ * Conditional macro definition for function calling type and variable type
+ * qualifiers.
+ */
+#if   ( (_MSC_VER >= 800) && (_M_IX86 >= 300) )
+
+/*
+ * Definitions for MS C8-32 (386/486) compiler
+ */
+#define _CRTAPI1 __cdecl
+#define _CRTAPI2 __cdecl
+
+#elif ( _MSC_VER == 600 )
+
+/*
+ * Definitions for old MS C6-386 compiler
+ */
+#define _CRTAPI1 _cdecl
+#define _CRTAPI2 _cdecl
+#define _M_IX86  300
+
+#else
+
+/*
+ * Other compilers (e.g., MIPS)
+ */
+#define _CRTAPI1
+#define _CRTAPI2
+
 #endif
 
 
 
+
 /* _getdiskfree structure (duplicated in DIRECT.H) */
 
 #ifndef _DISKFREE_T_DEFINED
@@ -96,7 +122,7 @@ extern unsigned int _osversion;
 
 /* function prototypes */
 
-unsigned _getdiskfree(unsigned, struct _diskfree_t *);
+unsigned _CRTAPI1 _getdiskfree(unsigned, struct _diskfree_t *);
 
 #if !__STDC__
 /* Non-ANSI name for compatibility */