diff --git a/ChangeLog b/ChangeLog
index fc0183b3..c48ebce9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2008-02-22  Eric Blake  <ebb9@byu.net>
+
+	Improve documentation for writing autotest suites.
+	* doc/autoconf.texi (Writing Testsuites) <AT_CHECK>: Mention that
+	checks must live inside a test group.
+	Reported by Christopher Hulbert.
+
 2008-02-21  Eric Blake  <ebb9@byu.net>
 
 	Sync git-version-gen from upstream.
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 07c66991..ea5997af 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -20227,6 +20227,8 @@ status 77, then the whole test group is skipped.  Otherwise, if this test
 fails, run shell commands @var{run-if-fail} or, if this test passes, run shell
 commands @var{run-if-pass}.
 
+This macro must be invoked in between @code{AT_SETUP} and @code{AT_CLEANUP}.
+
 @c Previously, we had this:
 @c  The @var{commands} @emph{must not} redirect the standard output, nor the
 @c  standard error.