diff --git a/README.md b/README.md
index f17d258..6a06f9b 100644
--- a/README.md
+++ b/README.md
@@ -27,7 +27,11 @@ cargo add northstar
 
 # Generating a key & certificate
 
+Run
 ```sh
 mkdir cert && cd cert
 openssl req -x509 -nodes -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365
 ```
+and enter your domain name (e.g. "localhost" for testing) as Common Name (CN).
+
+Alternatively, if you want to include multiple domains add something like `-addext "subjectAltName = DNS:localhost, DNS:example.org"`.