diff --git a/examples/vm/rootless-docker.md b/examples/vm/rootless-docker.md
index 6749ed1..7d387ff 100644
--- a/examples/vm/rootless-docker.md
+++ b/examples/vm/rootless-docker.md
@@ -11,6 +11,7 @@ As `root`:
 ```bash
  useradd -m rootless
  passwd rootless
+ apt-get install -y uidmap # Not mentioned but needed for docker rootless.
 ```
 
 - Install [`docker-ce`](https://docs.docker.com/engine/install/)