diff --git a/ChangeLog b/ChangeLog
index 2ef08f0ed1..2ee6a12704 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2018-08-10  Paul Eggert  <eggert@cs.ucla.edu>
+
+	regex: Gnulib unibyte RRI uses bytes not chars
+	Adjust the non-glibc code to agree with what Gawk needs for
+	rational range interpretation (RRI) for regular expression ranges.
+	In unibyte locales, Gawk wants ranges to use the underlying byte
+	rather than the character code point.  This change does not affect
+	glibc proper.
+	* posix/regcomp.c (parse_byte) [!LIBC && RE_ENABLE_I18N]:
+	In unibyte locales, use the byte value rather than
+	running it through btowc.
+
 2018-08-10  Joseph Myers  <joseph@codesourcery.com>
 
 	* sysdeps/generic/math-tests-snan.h: New file.
diff --git a/posix/regcomp.c b/posix/regcomp.c
index 3b0a3c6b6a..e81652f229 100644
--- a/posix/regcomp.c
+++ b/posix/regcomp.c
@@ -2684,15 +2684,14 @@ parse_dup_op (bin_tree_t *elem, re_string_t *regexp, re_dfa_t *dfa,
 
 # ifdef RE_ENABLE_I18N
 /* Convert the byte B to the corresponding wide character.  In a
-   unibyte locale, treat B as itself if it is an encoding error.
-   In a multibyte locale, return WEOF if B is an encoding error.  */
+   unibyte locale, treat B as itself.  In a multibyte locale, return
+   WEOF if B is an encoding error.  */
 static wint_t
 parse_byte (unsigned char b, re_charset_t *mbcset)
 {
-  wint_t wc = __btowc (b);
-  return wc == WEOF && !mbcset ? b : wc;
+  return mbcset == NULL ? b : __btowc (b);
 }
-#endif
+# endif
 
   /* Local function for parse_bracket_exp only used in case of NOT _LIBC.
      Build the range expression which starts from START_ELEM, and ends