diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 2dbe0d8bbac..cf74fc34f06 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2007-09-07  Thien-Thi Nguyen  <ttn@gnuvola.org>
+
+	* progmodes/autoconf.el (autoconf-definition-regexp):
+	Handle optional square brackets around definition name.
+
 2007-09-07  Johannes Weiner  <hannes@saeurebad.de>
 
 	* net/browse-url.el (browse-url-browser-function): Add elinks.
diff --git a/lisp/progmodes/autoconf.el b/lisp/progmodes/autoconf.el
index e01579917f6..d47a1c4d2cc 100644
--- a/lisp/progmodes/autoconf.el
+++ b/lisp/progmodes/autoconf.el
@@ -49,7 +49,7 @@
   '(("\\<dnl\\>" 0 '(11))))
 
 (defconst autoconf-definition-regexp
-  "AC_\\(SUBST\\|DEFINE\\(_UNQUOTED\\)?\\)(\\(\\sw+\\)")
+  "AC_\\(SUBST\\|DEFINE\\(_UNQUOTED\\)?\\)(\\[*\\(\\sw+\\)\\]*")
 
 (defvar autoconf-font-lock-keywords
   `(("\\_<A[CHMS]_\\sw+" . font-lock-keyword-face)