diff --git a/packages/core/test/effect/observability.test.ts b/packages/core/test/effect/observability.test.ts
index 0dcebba53f..5d7a35c1c0 100644
--- a/packages/core/test/effect/observability.test.ts
+++ b/packages/core/test/effect/observability.test.ts
@@ -16,6 +16,8 @@ test("measures an immediate event-loop block and stops sampling", async () => {
   const startedAt = performance.now()
   while (performance.now() - startedAt < 60) {}
   const maxMs = monitor.stop()
+  const stoppedAt = performance.now()
+  while (performance.now() - stoppedAt < 60) {}
   await Bun.sleep(40)
 
   expect(maxMs).toBeGreaterThanOrEqual(20)