Version

30.3.0

Steps to reproduce

• yarn add -D jest
• add jest.useFakeTimers().setSystemTime(new Date('2026-04-02T12:00:00Z')); on any test file
• yarn jest your-test-file.test.js

Expected behavior

System time is set with the specified Date value.

Actual behavior

 ● Test suite failed to run

    TypeError: now should be milliseconds since UNIX epoch

    > 1 | jest.useFakeTimers().setSystemTime(new Date('2026-04-02T12:00:00Z'));

Additional context

The issue seems to have been introduced by @sinonjs/fake-timers@15.3.0

Environment

System:
  OS: MacOS 26.4
Binaries:
  Node: v24.14.1
  Yarn: 4.13.0
npmPackages:
  jest: 30.3.0