diff --git a/docs/04-certificate-authority.md b/docs/04-certificate-authority.md
index 2a29257..68fdae2 100644
--- a/docs/04-certificate-authority.md
+++ b/docs/04-certificate-authority.md
@@ -104,7 +104,7 @@ Kubernetes uses a [special-purpose authorization mode](https://kubernetes.io/doc
 Generate a certificate and private key for each Kubernetes worker node:
 
 ```sh
-for instance in worker-0 worker-1 worker-2; do
+for instance in worker-{0..2}; do
 cat > ${instance}-csr.json <<EOF
 {
   "CN": "system:node:${instance}",
@@ -367,7 +367,7 @@ service-account.pem
 Copy the appropriate certificates and private keys to each worker instance:
 
 ```sh
-for instance in worker-0 worker-1 worker-2; do
+for instance in worker-{0..2}; do
   gcloud compute scp ca.pem ${instance}-key.pem ${instance}.pem ${instance}:~/
 done
 ```
@@ -375,7 +375,7 @@ done
 Copy the appropriate certificates and private keys to each controller instance:
 
 ```sh
-for instance in controller-0 controller-1 controller-2; do
+for instance in controller-{0..2}; do
   gcloud compute scp ca.pem ca-key.pem kubernetes-key.pem kubernetes.pem \
     service-account-key.pem service-account.pem ${instance}:~/
 done