diff --git a/README.md b/README.md
index 72e35b2f..bc77e361 100644
--- a/README.md
+++ b/README.md
@@ -156,6 +156,12 @@ part of the process you need to customise:
   install packages, chain into configuration management tools or do other
   image specific operations.
 
+* post-install.d: Run code in the chroot. This is a good place to perform
+  tasks you want to handle after the OS/application install but before the
+  first boot of the image. Some examples of use would be: Run chkconfig
+  to disable unneeded services and clean the cache left by the package
+  manager to reduce the size of the image.
+
 * first-boot.d: Runs inside the image before rc.local. Scripts from here are
   good for doing per-instance configuration based on cloud metadata.
 
diff --git a/bin/disk-image-create b/bin/disk-image-create
index 86ecdf1f..aa1eddb5 100755
--- a/bin/disk-image-create
+++ b/bin/disk-image-create
@@ -117,6 +117,7 @@ run_d_in_target pre-install
 do_extra_package_install
 # Call install scripts to pull in the software users want.
 run_d_in_target install
+run_d_in_target post-install
 prepare_first_boot
 finalise_base
 unmount_image
diff --git a/elements/dpkg/post-install.d/99-clean-up-cache b/elements/dpkg/post-install.d/99-clean-up-cache
new file mode 100755
index 00000000..2457f78d
--- /dev/null
+++ b/elements/dpkg/post-install.d/99-clean-up-cache
@@ -0,0 +1,6 @@
+#!/bin/bash
+# Do an apt-get clean. This will free some space.
+
+set -e
+
+apt-get clean