diff --git a/mqtt/sec/docker-compose.yml b/mqtt/sec/docker-compose.yml
index f803c8f..78a2681 100644
--- a/mqtt/sec/docker-compose.yml
+++ b/mqtt/sec/docker-compose.yml
@@ -59,7 +59,7 @@ services:
       if [ ! -f "$CONF" ]; then
         echo "Generating default mosquitto.conf...";
         cat <<EOF > $CONF
-listener ${MQTT_TLS_PORT:-8883}
+listener 8883
 protocol mqtt
 cafile /mosquitto/tls/ca.crt
 certfile /mosquitto/tls/server.crt