diff --git a/README.md b/README.md
index 86813a5..38f477f 100644
--- a/README.md
+++ b/README.md
@@ -74,7 +74,10 @@ Add the following to your `config.php`:
     ),
 
 This connects to the IMAP server on IP `127.0.0.1`.
-The default port is 143; however if you want to restrict the domain, you need to specify the port and set sslmode to `null`.
+The default port is 143. However, note that parameter order matters and if
+you want to restrict the domain (4th parameter), you need to also specify
+the port (2nd parameter) and sslmode (3rd parameter; set to `null` for
+insecure connection).
 If a domain name (e.g. example.com) is specified, then this makes sure that
 only users from this domain will be allowed to login. After successfull
 login the domain part will be striped and the rest used as username in