diff --git a/ChangeLog b/ChangeLog
index ee33573c..e13bde96 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2009-12-15  Joel E. Denny  <jdenny@clemson.edu>
+
+	autoconf: update to latest for fix of M4 detection.
+	Reported by Eric Blake.
+	* submodules/autoconf: Update.
+
 2009-12-15  Joel E. Denny  <jdenny@clemson.edu>
 
 	portability: use -DGNULIB_POSIXCHECK.
diff --git a/submodules/autoconf b/submodules/autoconf
index 936160f7..81074eaa 160000
--- a/submodules/autoconf
+++ b/submodules/autoconf
@@ -1 +1 @@
-Subproject commit 936160f7619cb7fddbc424bb5cb9a2f997d8e166
+Subproject commit 81074eaa201a289d11b6be05e0c78afbe5ff79f5