diff --git a/apps/web/src/routes/checks.ts b/apps/web/src/routes/checks.ts
index c100b0c..cc1c70f 100644
--- a/apps/web/src/routes/checks.ts
+++ b/apps/web/src/routes/checks.ts
@@ -26,7 +26,7 @@ export const checks = new Elysia()
       status_code: t.Optional(t.Number()),
       latency_ms:  t.Optional(t.Number()),
       up:          t.Boolean(),
-      error:       t.Optional(t.String()),
+      error:       t.Optional(t.Nullable(t.String())),
       meta:        t.Optional(t.Any()),
     }),
     detail: { summary: "Ingest result (monitor runner)", tags: ["internal"] },