diff --git a/mps/manual/source/design/index.rst b/mps/manual/source/design/index.rst
index 2e032a80b1e..716263dbb6b 100644
--- a/mps/manual/source/design/index.rst
+++ b/mps/manual/source/design/index.rst
@@ -7,6 +7,7 @@ Design
     :numbered:
 
     arena
+    bt
     protocol
     type
     version