diff --git a/todo.md b/todo.md
index 8bd6a7c..5576d7c 100644
--- a/todo.md
+++ b/todo.md
@@ -1,4 +1,5 @@
 - Don't turn client-side typos into new rendezvous points
+- ETag cache
 - Server-side hash?
 - Log / audit log?