diff --git a/README.md b/README.md
index c0832a97..922b5ced 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ The tool is distributed as source only — for now. You’ll have to download, c
 ```
 $ git clone https://github.com/DennisOSRM/hms-mqtt-publisher.git
 $ cd hms-mqtt-publisher
-$ cargo r --release [inverter] [mqtt broker] [mqtt user] [mqtt password]
+$ cargo r --release [inverter] [mqtt broker] [mqtt user] [mqtt password] [optional:mqtt port]
 ```
 ![image](https://github.com/lumapu/ahoy/assets/1067895/32c0b9b6-5aea-41e3-b9f8-161ce82fb99a)