diff --git a/devstack/README.rst b/devstack/README.rst
index 2634579d..f8c873e3 100644
--- a/devstack/README.rst
+++ b/devstack/README.rst
@@ -2,6 +2,10 @@
 Enabling in Devstack
 ====================
 
+**WARNING**: the stack.sh script must be run in a disposable VM that is not
+being created automatically, see the README.md file in the "devstack"
+repository.  See contrib/vagrant to create a vagrant VM.
+
 1. Download DevStack::
 
     git clone https://git.openstack.org/openstack-dev/devstack.git