diff --git a/lisp/nxml/rng-uri.el b/lisp/nxml/rng-uri.el
index 77fed8c32d..0a6fa39acb 100644
--- a/lisp/nxml/rng-uri.el
+++ b/lisp/nxml/rng-uri.el
@@ -68,7 +68,7 @@ Signal an error if URI is not a valid file URL."
 
 ;; pattern is either nil or match or replace
 (defun rng-uri-file-name-1 (uri pattern)
-  (unless (string-match "\\`\\(?:[^%]\\|%[[:xdigit:]]{2}\\)*\\'" uri)
+  (unless (string-match "\\`\\(?:[^%]\\|%[[:xdigit:]]\\{2\\}\\)*\\'" uri)
     (rng-uri-error "Bad escapes in URI `%s'" uri))
   (setq uri (rng-uri-unescape-multibyte uri))
   (let* ((components