# define ISALPHA(Ch) iswalpha (Ch)
# define TOUPPER(Ch) towupper (Ch)
#else
+# if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
+# define IN_CTYPE_DOMAIN(c) 1
+# else
+# define IN_CTYPE_DOMAIN(c) isascii(c)
+# endif
# define L_(Ch) Ch
# define UCHAR_TYPE unsigned char
# define STRING_TYPE char
-# define ISSPACE(Ch) isspace (Ch)
-# define ISALPHA(Ch) isalpha (Ch)
-# define TOUPPER(Ch) toupper (Ch)
+# define ISSPACE(Ch) (IN_CTYPE_DOMAIN (Ch) && isspace (Ch))
+# define ISALPHA(Ch) (IN_CTYPE_DOMAIN (Ch) && isalpha (Ch))
+# define TOUPPER(Ch) (IN_CTYPE_DOMAIN (Ch) ? toupper (Ch) : (Ch))
#endif
#ifdef __STDC__