diff --git a/tutorials/mqtt/mqtt-client/mongoose_mqtt.c b/tutorials/mqtt/mqtt-client/mongoose_mqtt.c
index e7b27670..a05257d1 100644
--- a/tutorials/mqtt/mqtt-client/mongoose_mqtt.c
+++ b/tutorials/mqtt/mqtt-client/mongoose_mqtt.c
@@ -12,7 +12,7 @@
 #define MQTT_QOS 1
 #define MQTT_RECONNECT_PERIOD_MS 3000
 
-#define TLS_CA ""
+#define TLS_CA ""  // Use https://mongoose.ws/tls/
 #define TLS_KEY ""
 #define TLS_CRT ""