diff --git a/debian/changelog b/debian/changelog
index 239d5aa5..5dca7427 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,16 @@
+livecd-rootfs (2.454) UNRELEASED; urgency=medium
+
+  * live-build/functions: mount tmpfs on /var/cache/apt and var/lib/apt, so
+    we don't have to leave empty space in our derivative images for packages
+    that have been downloaded/installed/removed.  This normally isn't
+    relevant for the installed system, since the root filesystem will
+    auto-expand in place on the target disk, but lets us ship smaller
+    images.
+  * live-build/functions: also call 'apt-get update' after mounting the
+    blank /var/lib/apt.
+
+ -- Steve Langasek <steve.langasek@ubuntu.com>  Tue, 12 Sep 2017 14:33:02 -0700
+
 livecd-rootfs (2.453) artful; urgency=medium
 
   [ Chris Glass ]
diff --git a/live-build/functions b/live-build/functions
index d0bda550..868fcdb2 100644
--- a/live-build/functions
+++ b/live-build/functions
@@ -83,8 +83,11 @@ setup_mountpoint() {
     mount proc-live -t proc "$mountpoint/proc"
     mount sysfs-live -t sysfs "$mountpoint/sys"
     mount -t tmpfs none "$mountpoint/tmp"
+    mount -t tmpfs none "$mountpoint/var/lib/apt"
+    mount -t tmpfs none "$mountpoint/var/cache/apt"
     mv "$mountpoint/etc/resolv.conf" resolv.conf.tmp
     cp /etc/resolv.conf "$mountpoint/etc/resolv.conf"
+    chroot "$mountpoint" apt-get update
 
 }
 
diff --git a/live-build/ubuntu-cpc/hooks/032-root-squashfs.binary b/live-build/ubuntu-cpc/hooks/032-root-squashfs.binary
index 8c1580ea..703b2b15 100755
--- a/live-build/ubuntu-cpc/hooks/032-root-squashfs.binary
+++ b/live-build/ubuntu-cpc/hooks/032-root-squashfs.binary
@@ -41,6 +41,8 @@ umount "binary/boot/squashfs.dir/proc"
 umount "binary/boot/squashfs.dir/sys"
 umount -R "binary/boot/squashfs.dir/dev"
 umount "binary/boot/squashfs.dir/tmp"
+umount "binary/boot/squashfs.dir/var/lib/apt"
+umount "binary/boot/squashfs.dir/var/cache/apt"
 
 squashfs_f="${PWD}/livecd.ubuntu-cpc.squashfs"
 squashfs_f_manifest="${squashfs_f}.manifest"