diff --git a/README.md b/README.md
index 81c9cb4..35f3310 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,8 @@ Babushka pre-installed.
 
 When using ANSIBLE=1, an optional ANSIBLE_VERSION parameter may be passed that will specify which version of ansible to install. By default it will install the latest Ansible.
 
+Additional packages to be installed can be specified with the ADDPACKAGES variable:
+
 ```sh
 ADDPACKAGES="aptitude htop" \
 make trusty
@@ -65,6 +67,8 @@ Will build a Ubuntu Trusty x86_64 box with aptitude and htop as additional
 packages pre-installed. You can also specify the packages in a file
 trusty_packages.
 
+Note: ADDPACKAGES is currently only implemented for flavors of debian.
+
 ## Pre built base boxes
 
 _**NOTE:** None of the base boxes below have a provisioner pre-installed_