diff --git a/server/lib/set-headers-for-date-temporal-context.js b/server/lib/set-headers-for-date-temporal-context.js
index 4150356..a72f63f 100644
--- a/server/lib/set-headers-for-date-temporal-context.js
+++ b/server/lib/set-headers-for-date-temporal-context.js
@@ -5,17 +5,19 @@ const assert = require('assert');
 const { getUtcStartOfDayTs } = require('matrix-public-archive-shared/lib/timestamp-utilities');
 
 // `X-Date-Temporal-Context` indicates the temporal context of the content, whether it
-// is related to past, present, or future *day*. This is useful for caching purposes so
-// you can heavily cache past content, but not present/future.
+// is related to past, present, or future *day*.
+//
+// This is useful for caching purposes so you can heavily cache past content, but not
+// present/future.
 function setHeadersForDateTemporalContext({ res, nowTs, comparedToUrlDate: { yyyy, mm, dd } }) {
   assert(res);
-  assert(nowTs);
-  assert(yyyy);
-  assert(mm);
-  assert(dd);
+  assert(Number.isInteger(nowTs));
+  assert(Number.isInteger(yyyy));
+  assert(Number.isInteger(mm));
+  assert(Number.isInteger(dd));
 
-  // We use the start of the UTC day so we can compare apples to apples and see whether
-  // yyyy-mm-dd is the past/present/future day.
+  // We use the start of the UTC day so we can compare apples to apples with a new date
+  // constructed with yyyy-mm-dd (no time occured since the start of the day)
   const startOfTodayTs = getUtcStartOfDayTs(nowTs);
   const compareTs = Date.UTC(yyyy, mm, dd);