diff --git a/debian/changelog b/debian/changelog
index 7536549b..2a53c5cb 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -2,7 +2,8 @@ livecd-rootfs (2.408.16) xenial; urgency=medium
 
   * live-build/ubuntu-cpc/functions: call apt-get update in the chroot
     after mounting a blank /var/lib/apt, so that further operations work
-    as expected.
+    as expected; otherwise, 'apt-get purge ^grub-.*' fails on s390x because
+    no such packages are known to apt.
 
  -- Steve Langasek <steve.langasek@ubuntu.com>  Tue, 12 Sep 2017 13:25:58 -0700