diff --git a/Readme.md b/Readme.md
index d451818..7af51b6 100644
--- a/Readme.md
+++ b/Readme.md
@@ -29,5 +29,5 @@ Those measure can be shared by MQTT(s). MQTT details (server, username, passwd,
 
 To interface with BMP180, the following library should be installed into Arduino environment: https://github.com/mmaret/BMP180_Breakout_Arduino_Library/archive/master.zip
 
-To use mqtt, the Adafruit Mqtt library should be installed.
+To use mqtt, a fork of the Adafruit Mqtt library should be installed (https://github.com/shmuelzon/Adafruit_MQTT_Library/tree/support_retain).
 This have been tested against a mosquitto server