diff --git a/frontend/src/lib/timeline/timelineMeta.ts b/frontend/src/lib/timeline/timelineMeta.ts
index 7052c405..38b40ea7 100644
--- a/frontend/src/lib/timeline/timelineMeta.ts
+++ b/frontend/src/lib/timeline/timelineMeta.ts
@@ -21,11 +21,18 @@ export interface TimelineMeta {
  */
 export function timelineMeta(timeline: TimelineDTO): TimelineMeta {
 	const years = timeline.years;
-	const allEntries = [...years.flatMap((y) => y.entries), ...timeline.undated];
+	let letterCount = 0;
+	let eventCount = 0;
+	const tally = (e: TimelineDTO['undated'][number]) => {
+		if (e.kind === 'LETTER') letterCount += 1;
+		else if (e.kind === 'EVENT') eventCount += 1;
+	};
+	for (const y of years) for (const e of y.entries) tally(e);
+	for (const e of timeline.undated) tally(e);
 	return {
 		firstYear: years.length ? years[0].year : null,
 		lastYear: years.length ? years[years.length - 1].year : null,
-		letterCount: allEntries.filter((e) => e.kind === 'LETTER').length,
-		eventCount: allEntries.filter((e) => e.kind === 'EVENT').length
+		letterCount,
+		eventCount
 	};
 }