diff --git a/README.md b/README.md
index e2f5894d6..6de48f56b 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@ Version 4.0.0 [![Actions Status](https://github.com/redboltz/async_mqtt/workflow
 This is Boost.Asio oriented asynchronous MQTT communication library. You can use async_mqtt to develop not only your MQTT client application but also your server (e.g. broker).
 Based on https://github.com/redboltz/mqtt_cpp experience, there are many improvements. See overview.
 
-Document is https://github.com/redboltz/async_mqtt/blob/doc/README.md
+Document is https://github.com/redboltz/async_mqtt/blob/doc/README.adoc
 
 # Overview