diff --git a/POSTINSTALL.md b/POSTINSTALL.md
index 0277f66..f5da42a 100644
--- a/POSTINSTALL.md
+++ b/POSTINSTALL.md
@@ -1,5 +1,5 @@
 Account ids are created with the username and the second level domain under which the
-app is installed e.g. `@$CLOUDRON-USERNAME@$CLOUDRON-APP-DOMAIN`.
+app is installed e.g. `@$CLOUDRON-USERNAME:$CLOUDRON-APP-DOMAIN`.
 
 For federation to work, the delegation URI `https://$CLOUDRON-APP-DOMAIN/.well-known/matrix/server`
 must be configured. See the [docs](https://docs.cloudron.io/apps/synapse/#post-installation) on how to do this.