diff --git a/tests/roles/bootstrap-host/templates/user_variables.aio.yml.j2 b/tests/roles/bootstrap-host/templates/user_variables.aio.yml.j2
index 0af14cd1e5..0cd8524c52 100644
--- a/tests/roles/bootstrap-host/templates/user_variables.aio.yml.j2
+++ b/tests/roles/bootstrap-host/templates/user_variables.aio.yml.j2
@@ -109,3 +109,6 @@ uca_apt_repo_url: {{ uca_apt_repo_url }}
 repo_build_pip_no_binary:
   - libvirt-python
 
+# The container backing store is set to 'overlayfs' to speed up the
+# AIO build time.
+lxc_container_backing_store: overlayfs