diff --git a/docker2mqtt/docker2mqtt.py b/docker2mqtt/docker2mqtt.py
index 264ee01..c28e956 100755
--- a/docker2mqtt/docker2mqtt.py
+++ b/docker2mqtt/docker2mqtt.py
@@ -1196,6 +1196,7 @@ def main() -> None:
     parser.add_argument(
         "--port",
         default=MQTT_PORT_DEFAULT,
+        type=int,
         help="Port or IP address of the MQTT broker (default: 1883)",
     )
     parser.add_argument(