diff --git a/org-ql.el b/org-ql.el
index 6399d22..f5574b6 100644
--- a/org-ql.el
+++ b/org-ql.el
@@ -286,6 +286,8 @@ replace the clause with a preamble."
                                    ;; Return nil
                                    nil))
                                 (`(todo . ,(and todo-keywords (guard todo-keywords)))
+                                 ;; FIXME: With case-folding, a query like (todo "WAITING")
+                                 ;; can find a non-todo heading named "Waiting".
                                  (let* ((regexps (--map (list 'regexp
                                                               (format org-heading-keyword-regexp-format it))
                                                         todo-keywords))