diff --git a/README.md b/README.md
index beb5ec2..4a99a2f 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,10 @@ TypeScript and JavaScript, in both node.js and the browser. The
 implementation techniques herein are the subject of a forthcoming
 paper.
 
+**IMPORTANT: Use branch `typescript1` when cloning this project from git:**
+
+    git clone -b typescript1 https://git.syndicate-lang.org/syndicate-lang/syndicate-js
+
 ## Building
 
 This project uses [`yarn`](https://yarnpkg.com/), not `npm`.