tests/mqttd: extract the client id from the correct offsetbagder/mqttd

Closes #6334

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/server/mqttd.c b/tests/server/mqttd.c
index 1f4344ac0..aec4a099b 100644
--- a/tests/server/mqttd.c
+++ b/tests/server/mqttd.c
@@ -537,7 +537,7 @@ static curl_socket_t mqttit(curl_socket_t fd)
         logmsg("Too large client id");
         goto end;
       }
-      memcpy(client_id, &buffer[14], payload_len);
+      memcpy(client_id, &buffer[12], payload_len);
       client_id[payload_len] = 0;
 
       logmsg("MQTT client connect accepted: %s", client_id);