diff --git a/ext/readline/readline.c b/ext/readline/readline.c
index 130ea9ce59..b03f04d2fa 100644
--- a/ext/readline/readline.c
+++ b/ext/readline/readline.c
@@ -1080,7 +1080,7 @@ readline_char_is_quoted(char *text, int byte_index)
                  byte_index, len);
     }
 
-    str = rb_locale_str_new_cstr(text);
+    str = rb_locale_str_new(text, len);
     char_index = rb_str_sublen(str, byte_index);
     result = rb_funcall(proc, id_call, 2, str, LONG2FIX(char_index));
     return RTEST(result);