1 files changed, 1 insertions, 1 deletions

diff --git a/lisp/mail/sendmail.el b/lisp/mail/sendmail.el
index 1da33a43eb8..e71f98282ad 100644
--- a/lisp/mail/sendmail.el
+++ b/lisp/mail/sendmail.el
@@ -249,7 +249,7 @@ regardless of what part of it (if any) is included in the cited text.")
 
 ;;;###autoload
 (defcustom mail-citation-prefix-regexp
-  (purecopy "\\([ \t]*\\(\\w\\|[_.]\\)+>+\\|[ \t]*[]>|]\\)+")
+  (purecopy "\\([ \t]*\\(\\w\\|[_.]\\)+>+\\|[ \t]*[>|]\\)+")
   "Regular expression to match a citation prefix plus whitespace.
 It should match whatever sort of citation prefixes you want to handle,
 with whitespace before and after; it should also match just whitespace.