diff --git a/lib/queries.ts b/lib/queries.ts
index 3a81039..0f46513 100644
--- a/lib/queries.ts
+++ b/lib/queries.ts
@@ -107,7 +107,7 @@ export async function getTrends(
   );
 
   return rows.map((r) => ({
-    date: String(r.date).slice(0, 10),
+    date: r.date instanceof Date ? r.date.toISOString().slice(0, 10) : String(r.date).slice(0, 10),
     calls: Number(r.calls),
     prompt_tokens: Number(r.prompt_tokens),
     completion_tokens: Number(r.completion_tokens),