diff --git a/scheme/cyclone/cps-optimizations.sld b/scheme/cyclone/cps-optimizations.sld
index 1cb20d9b..689e4d19 100644
--- a/scheme/cyclone/cps-optimizations.sld
+++ b/scheme/cyclone/cps-optimizations.sld
@@ -197,6 +197,7 @@
       ))
 
     (define-record-type <analysis-db-function>
+TODO: well-known (see Dybvig's paper)
       (%adb:make-fnc simple unused-params assigned-to-var side-effects)
       adb:function?
       (simple adbf:simple adbf:set-simple!)