diff --git a/m4/ChangeLog b/m4/ChangeLog
index 742361f75..789f5b3ab 100644
--- a/m4/ChangeLog
+++ b/m4/ChangeLog
@@ -1,3 +1,8 @@
+2005-10-07  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* stdbool.m4 (AC_HEADER_STDBOOL): Add an "#ifdef __xlc__" test,
+	since yesterday's attempt didn't work.
+
 2005-10-06  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* stdbool.m4 (AC_HEADER_STDBOOL): Check that bool