diff --git a/README.md b/README.md
index 1a3dd4b..67a5bb3 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@
 
 This package provides Wrike OAuth 2.0 support for the PHP League's [OAuth 2.0 Client](https://github.com/thephpleague/oauth2-client).
 
+IMPORTANT NOTE: the versions 2.x support the v4 API, prior versions the v3 API
+
 ## Installation
 
 ```