-#ifndef PARAMS
-# if defined (__GNUC__) || __STDC__
-# define PARAMS(Args) Args
-# else
-# define PARAMS(Args) ()
-# endif
+#include <stddef.h>
+
+/* Avoid a clash of our mbswidth() with a function of the same name defined
+ in UnixWare 7.1.1 <wchar.h>. We need this #include before the #define
+ below.
+ However, we don't want to #include <wchar.h> on all platforms because
+ - Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
+ <wchar.h>.
+ - BSD/OS 4.1 has a bug: <stdio.h> and <time.h> must be included before
+ <wchar.h>. */
+#if HAVE_DECL_MBSWIDTH_IN_WCHAR_H
+# include <wchar.h>