diff --git a/src/cron/isolated-agent/run.payload-fallbacks.test.ts b/src/cron/isolated-agent/run.payload-fallbacks.test.ts
index 24d69197751..e0db25f70a5 100644
--- a/src/cron/isolated-agent/run.payload-fallbacks.test.ts
+++ b/src/cron/isolated-agent/run.payload-fallbacks.test.ts
@@ -20,7 +20,7 @@ function requireModelFallbackRequest(): {
   provider?: string;
   model?: string;
 } {
-  const request = runWithModelFallbackMock.mock.calls[0]?.[0] as
+  const request = runWithModelFallbackMock.mock.calls.at(0)?.[0] as
     | {
         fallbacksOverride?: string[];
         provider?: string;