diff --git a/ChangeLog b/ChangeLog
index dc005002..35eab3b3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2008-04-23  Eric Blake  <ebb9@byu.net>
+
+	Revert prior patch, by working around autoconf regression.
+	* tests/output.at (m4_expand): Add workaround for autoconf 2.62.
+	("Output file name: ("): Uncomment test.
+	("Output file name: )"): Likewise.
+	Based on an idea from Noah Misch.
+
 2008-04-21  Joel E. Denny  <jdenny@ces.clemson.edu>
 
 	Work-around an Autoconf 2.62 AT_SETUP bug that was not present in
diff --git a/tests/output.at b/tests/output.at
index e1e4dc4c..6e21dc93 100644
--- a/tests/output.at
+++ b/tests/output.at
@@ -186,9 +186,13 @@ AT_CLEANUP
 # Notice that the header file name here cannot contain
 # `"' since FILENAME in `#include "FILENAME"' cannot.
 AT_CHECK_OUTPUT_FILE_NAME([[`~!@#$%^&*()-=_+{}[]|\:;<>, .']])
-dnl Autoconf 2.62's AT_SETUP can't handle these, but they worked fine in 2.61.
-dnl AT_CHECK_OUTPUT_FILE_NAME([[(]])
-dnl AT_CHECK_OUTPUT_FILE_NAME([[)]])
+dnl Work around a bug in m4_expand that broke AT_SETUP in autoconf 2.62,
+dnl by using the definition from 2.63.
+m4_define([m4_expand], [_$0(-=<{($1)}>=-)])
+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([[@{]])