diff --git a/server/TODO b/server/TODO
index 6a10241..38de305 100644
--- a/server/TODO
+++ b/server/TODO
@@ -17,6 +17,11 @@
     - straight matching of sexps without translation gives a ~5% speedup
     - checking for "post" first in message_of_sexp gives a ~3% speedup
 
+ - fix the Json merge operator. I don't think there can be a
+   generally-acceptable merge, so come up with a sensible one for
+   config perhaps? The main problem is to do with setting elements of
+   an array; it uses `[+]` too much.
+
 ## General
 
 Cope with possibility of duplicate uuid, in e.g. queue/fanout/direct.