--- tr-6.7/str.c.orig	Sun May 10 10:17:16 2020
+++ tr-6.7/str.c	Sun May 10 10:25:37 2020
@@ -147,6 +147,90 @@
 	int *set;
 } CLASS;
 
+#undef isalnum
+#undef isalpha
+#undef iscntrl
+#undef isdigit
+#undef isgraph
+#undef islower
+#undef isprint
+#undef ispunct
+#undef isspace
+#undef isupper
+#undef isxdigit
+
+int
+isalnum(int c)
+{
+	return (_ctype_[(int)(c)] & (_U | _L | _N));
+}
+
+int
+isalpha(int c)
+{
+	return (_ctype_[(int)(c)] & (_U | _L));
+}
+
+int
+isblank(int c)
+{
+	return (c == ' ' || c == '\t');
+}
+
+int
+iscntrl(int c)
+{
+	return (_ctype_[(int)(c)] & (_C));
+}
+
+int
+isdigit(int c)
+{
+	return (_ctype_[(int)(c)] & (_N));
+}
+
+int
+isgraph(int c)
+{
+	return (_ctype_[(int)(c)] & (_P | _U | _L | _N));
+}
+
+int
+islower(int c)
+{
+	return ((_ctype_[(int)(c)] & (_U | _L)) == _L);
+}
+
+int
+isprint(int c)
+{
+	return (_ctype_[(int)(c)] & (_P | _U | _L | _N | _B));
+}
+
+int
+ispunct(int c)
+{
+	return (_ctype_[(int)(c)] & (_P));
+}
+
+int
+isspace(int c)
+{
+	return (_ctype_[(int)(c)] & (_S));
+}
+
+int
+isupper(int c)
+{
+	return ((_ctype_[(int)(c)] & (_U | _L)) == _U);
+}
+
+int
+isxdigit(int c)
+{
+	return (_ctype_[(int)(c)] & (_N | _X));
+}
+
 static CLASS classes[] = {
 	{ "alnum",  isalnum,  },
 	{ "alpha",  isalpha,  },