diff --git a/TODO b/TODO
index e69de29b..fb82e4c2 100644
--- a/TODO
+++ b/TODO
@@ -0,0 +1,4 @@
+- should space be required before the closing ### in an ATX header?
+  http://talk.commonmark.org/t/atx-header-closing-space-confusion/333
+  perhaps so - symmetrically with beginning, and for equally good reasons
+