diff --git a/Documentation/cloud-config.md b/Documentation/cloud-config.md
index b13874b..b3e329b 100644
--- a/Documentation/cloud-config.md
+++ b/Documentation/cloud-config.md
@@ -40,7 +40,7 @@ CoreOS tries to conform to each platform's native method to provide user data. E
 #### etcd
 
 The `coreos.etcd.*` parameters will be translated to a partial systemd unit acting as an etcd configuration file.
-We can use the templating feature of coreos-cloudinit to automate etcd configuration with the `$private_ipv4` and `$public_ipv4` fields. For example, the following cloud-config document...
+If the platform environment supports the templating feature of coreos-cloudinit it is possible to automate etcd configuration with the `$private_ipv4` and `$public_ipv4` fields. For example, the following cloud-config document...
 
 ```yaml
 #cloud-config
@@ -68,6 +68,8 @@ Environment="ETCD_PEER_ADDR=192.0.2.13:7001"
 For more information about the available configuration parameters, see the [etcd documentation][etcd-config].
 Note that hyphens in the coreos.etcd.* keys are mapped to underscores.
 
+_Note: The `$private_ipv4` and `$public_ipv4` substitution variables referenced in other documents are only supported on Amazon EC2, Google Compute Engine, OpenStack, Rackspace, and Vagrant._
+
 [etcd-config]: https://github.com/coreos/etcd/blob/master/Documentation/configuration.md
 
 #### fleet