diff --git a/src/telegram/monitor.ts b/src/telegram/monitor.ts
index 2b5bdae8f4c..16c2db551b4 100644
--- a/src/telegram/monitor.ts
+++ b/src/telegram/monitor.ts
@@ -70,6 +70,9 @@ const POLL_WATCHDOG_INTERVAL_MS = 30_000;
 type TelegramBot = ReturnType<typeof createTelegramBot>;
 
 function normalizePersistedUpdateId(value: number | null): number | null {
+  if (value === null) {
+    return null;
+  }
   if (!Number.isSafeInteger(value) || value < 0) {
     return null;
   }