diff --git a/README.md b/README.md
index 95ba305a..e2776a21 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,8 @@ This is an example of how to build a kube-like controller with a single type.
 
 ## Running
 
+**Prerequisite**: Since the sample-controller uses `apps/v1` deployments, the Kubernetes cluster version should be greater than 1.9.
+
 ```sh
 # assumes you have a working kubeconfig, not required if operating in-cluster
 $ go run *.go -kubeconfig=$HOME/.kube/config