diff --git a/lib/hk-util.js b/lib/hk-util.js
index b28cad497..e9943f1c1 100644
--- a/lib/hk-util.js
+++ b/lib/hk-util.js
@@ -672,6 +672,7 @@ const handleGetHistoryRange = function (Env, Server, seq, userId, parsed) {
 
         if (!Array.isArray(messages)) { messages = []; }
 
+        // FIXME this reduction could be done in the worker instead of the main process
         var toSend = [];
         if (typeof (desiredMessages) === "number") {
             toSend = messages.slice(-desiredMessages);