diff --git a/ChangeLog b/ChangeLog
index 76146450..aa13e016 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2009-04-06  Eric Blake  <ebb9@byu.net>
+
+	Work around autoconf 2.63b bug in testsuite.
+	* tests/output.at (AT_CHECK_OUTPUT_FILE_NAME): Avoid tripping
+	autoconf bug related to # in test.
+
 2009-04-06  Joel E. Denny  <jdenny@ces.clemson.edu>
 
 	* NEWS (2.5): New section.  Describe new -D/--define feature.
diff --git a/tests/output.at b/tests/output.at
index fe5708c4..971df1e9 100644
--- a/tests/output.at
+++ b/tests/output.at
@@ -1,6 +1,6 @@
 # Checking the output filenames.                    -*- Autotest -*-
-# Copyright (C) 2000, 2001, 2002, 2005, 2006, 2007, 2008 Free Software
-# Foundation, Inc.
+# Copyright (C) 2000, 2001, 2002, 2005, 2006, 2007, 2008, 2009 Free
+# Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -214,7 +214,7 @@ m4_define([_m4_expand],
 [m4_changequote([-=<{(], [)}>=-])$1m4_changequote([, ])])])
 AT_CHECK_OUTPUT_FILE_NAME([[(]])
 AT_CHECK_OUTPUT_FILE_NAME([[)]])
-AT_CHECK_OUTPUT_FILE_NAME([[#]])
+AT_CHECK_OUTPUT_FILE_NAME([[@%:@]])
 AT_CHECK_OUTPUT_FILE_NAME([[@@]])
 AT_CHECK_OUTPUT_FILE_NAME([[@{]])
 AT_CHECK_OUTPUT_FILE_NAME([[@}]])