diff --git a/README.md b/README.md
index 8734bbc47..55ffadd8f 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,8 @@
 [![Build Status](https://travis-ci.org/openstreetmap/iD.svg?branch=master)](https://travis-ci.org/openstreetmap/iD)
 [![Greenkeeper badge](https://badges.greenkeeper.io/openstreetmap/iD.svg)](https://greenkeeper.io/)
 
+:warning: _The [`master`](https://github.com/openstreetmap/iD/tree/master) branch is undergoing significant breaking changes for v3 over the next few months. [`2.x`](https://github.com/openstreetmap/iD/tree/2.x) is considerably more stable and is currently the recommended branch for downstream development._
+
 ## Basics
 
 * iD is a JavaScript [OpenStreetMap](https://www.openstreetmap.org/) editor.