diff --git a/TODO b/TODO
index e4ac504463126fdcdba56c9a198dac029cf9e195..c137d8f777571d267c56a11996fc62196cf0da47 100644
--- a/TODO
+++ b/TODO
@@ -1,5 +1,7 @@
 Roughly in order of importance.                                     -*-org-*-
 
+* Fix lattice.neighbors() when lattice has lower dimensionality than the space.
+
 * Document the order of sites/orbitals in finalized builders
 
 * Add calculation of current density