diff --git a/p6.md b/p6.md
index 65175a94b849dd86e05f5e69d7c7b0c616698ab6..b53b1c5f6fd77a8efb6e0ef34066835fe18a0224 100644
--- a/p6.md
+++ b/p6.md
@@ -26,7 +26,8 @@ serializability. Writes from transactions that abort do not affect the
 KV.
 
 Finally, in the *tree* type, you will create a shared tree that
-supports concurrent modifications via simple mutations.
+supports concurrent modifications via simple mutations. You build this
+entirely from scratch.
 
 You will build your tango support in a new `p6/tango` module. Your
 applications will call the tango module API to access the shared log.