diff --git a/POSTINSTALL.md b/POSTINSTALL.md
index 6b19377..83e8e9f 100644
--- a/POSTINSTALL.md
+++ b/POSTINSTALL.md
@@ -1,5 +1,5 @@
 Accounts are created with the username and the subdomain under which this app is installed
- e.g. `@$CLOUDRON-USERNAME@$CLOUDRON-APP-DOMAIN`. Note that Mastodon does NOT allow this subdomain
+ e.g. `@$CLOUDRON-USERNAME@$CLOUDRON-APP-FQDN`. Note that Mastodon does NOT allow this subdomain
 to be changed later as it breaks federation. So, you have to set up Mastodon in the correct
 subdomain from the get-go.