diff --git a/README.md b/README.md
index 68144b2..c47ccbb 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,11 @@
 # script collection for certbot dns authenication for domains hosted by inwx.de
 
+This script collectin is in alpha state and only useable on linux systems.
+Tested with debian 9 and ubuntu 16.04.
+
+
 ## example usage
 
 ```
-ertbot certonly --dry-run --manual --preferred-challenges=dns --manual-auth-hook ./certbot-dns-auth.sh -d example.com
+certbot certonly --dry-run --manual --preferred-challenges=dns --manual-auth-hook ./certbot-dns-auth.sh -d example.com
 ```