diff --git a/reference/configuration.html.markerb b/reference/configuration.html.markerb
index 67d1756fab..e8d0cc061a 100644
--- a/reference/configuration.html.markerb
+++ b/reference/configuration.html.markerb
@@ -181,9 +181,19 @@ To run a command in a temporary Machine—using the app's successfully built
 
 The `release_command` value replaces `CMD` in the temporary Machine. This is useful for running database migrations before app Machines are created or updated with the new release. Note that the Docker image's `ENTRYPOINT` is not overridden by the `release_command`; `ENTRYPOINT` always runs.
 
-The temporary Machine has full access to the network, environment variables and secrets, but *not* to persistent volumes. Changes made to the file system on the temporary Machine will not be retained or deployed. The building/compiling of your project should be done in your Dockerfile. If you need to modify persistent volumes or configure your application, consider making use of `CMD` or `ENTRYPOINT` in your Dockerfile, or of a [process group command](#the-processes-section).
+By default, the temporary Machine has full access to the network, environment variables and secrets, but *not* to persistent volumes. Changes made to the file system on the temporary Machine will not be retained or deployed. The building/compiling of your project should be done in your Dockerfile. If you need to modify persistent volumes or configure your application, consider making use of `CMD` or `ENTRYPOINT` in your Dockerfile, or of a [process group command](#the-processes-section).
 
 The temporary Machine inherits the size from the largest Machine in the default process group of the app as of flyctl v0.0.508 (they also default larger on empty/new apps, using the Machine `shared-cpu-2x` preset). The default process group is defined as either the `app` process, or the first process group in alphabetical order (if an `app` process is not present).
+It is also possible to explicitly define the Machine size by setting `[deploy.release_command_vm]`  like in:
+
+```toml
+[deploy]
+  release_command = "bin/rails db:prepare"
+
+  [deploy.release_command_vm]
+    size = "performance-1x"
+    memory = "8gb"
+```
 
 A non-zero exit status from this command will stop the deployment. `fly deploy` will display logs from the command. Logs are available via `fly logs` as well.