diff --git a/ChangeLog b/ChangeLog
index f2408a4..8fb4937 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2018-10-20  Peter Kokot  <peterkokot@gmail.com>
+
+	* config.sub: Direct diagnostic output to standard error.
+
 2018-10-17  Urs Janßen <urs@tin.org>
 
 	* config.sub: Fix comment typos.
diff --git a/config.sub b/config.sub
index 2d5bbee..f208558 100755
--- a/config.sub
+++ b/config.sub
@@ -89,7 +89,7 @@ while test $# -gt 0 ; do
     - )	# Use stdin as input.
        break ;;
     -* )
-       echo "$me: invalid option $1$help"
+       echo "$me: invalid option $1$help" >&2
        exit 1 ;;
 
     *local*)