diff --git a/.dir-locals.el b/.dir-locals.el
index f8ee130..b934213 100644
--- a/.dir-locals.el
+++ b/.dir-locals.el
@@ -9,7 +9,7 @@
      ;; For use with 'bug-reference-prog-mode'.
      (bug-reference-url-format . "https://gitlab.com/nonguix/nonguix/issues/%s")
      (bug-reference-bug-regexp
-      . "#[0-9]+")))
+      . "\\(#\\([0-9]+\\)\\)")))
  (c-mode          . ((c-file-style . "gnu")))
  (scheme-mode
   .