diff --git a/doc/0-chirpstack/2-mosquitto-tls.md b/doc/0-chirpstack/2-mosquitto-tls.md
index e27087f..4e7481e 100644
--- a/doc/0-chirpstack/2-mosquitto-tls.md
+++ b/doc/0-chirpstack/2-mosquitto-tls.md
@@ -193,7 +193,7 @@ On the ChirpStack server, open a terminal window and subscribe to all messages:
 mosquitto_sub  -h localhost -t "#" -v -d
 ```
 
-Keep the terminal open, and on the test machine, send a message to the `us915_1/gateway/<GATEWAY_ID>/test` topic, substituting `<GATEWAY_ID>` accordingly:
+Keep the terminal open, and on the test machine, send a message to the `us915_1/gateway/<GATEWAY_ID>/test` topic, substituting `your.site.name` and `<GATEWAY_ID>` accordingly:
 
 ```sh
 mosquitto_pub \