diff --git a/src/or/circuituse.c b/src/or/circuituse.c
index c48020115..91f75733a 100644
--- a/src/or/circuituse.c
+++ b/src/or/circuituse.c
@@ -1555,6 +1555,8 @@ optimistic_data_enabled(void)
 {
   const or_options_t *options = get_options();
   if (options->OptimisticData < 0) {
+    /* XXX023 consider having auto default to 1 rather than 0 before
+     * the 0.2.3 branch goes stable. See bug 3617. -RD */
     const int32_t enabled =
       networkstatus_get_param(NULL, "UseOptimisticData", 0, 0, 1);
     return (int)enabled;