diff --git a/src/todo.txt b/src/todo.txt
index 2fd9f93..9b915ab 100644
--- a/src/todo.txt
+++ b/src/todo.txt
@@ -2,6 +2,8 @@
   actual bindings list, to debug the stuff that happens.
 - PRIO 2 : resolve Arachne memory usage issue. Why is it using so much memory?
   Recode stuff to memAlloc/memFree and determine max usage, leakage etc.
+- Arachne seems to trip over claims with empty prec sets. Maybe we
+  simply should not test these.
 - soph segfaults at no switch or -r4 (-r3 is okay??) using non-debug version.
 - Splice/AS does not work well because priority key search stumbles over the
   public key search stuff. That is a flaw in the heuristic: we should not look