Apple’s latest marketing campaign — “Privacy. That’s iPhone” — made us raise our eyebrows.

It’s true that Apple has an impressive track record of protecting users’ privacy, from end-to-end encryption on iMessage to anti-tracking in Safari.

But a key feature in iPhones has us worried, and makes their latest slogan ring a bit hollow.

Each iPhone that Apple sells comes with a unique ID (called an “identifier for advertisers” or IDFA), which lets advertisers track the actions users take when they use apps. It’s like a salesperson following you from store to store while you shop and recording each thing you look at. Not very private at all.

The good news: You can turn this feature off. The bad news: Most people don’t know that feature even exists, let alone that they should turn it off. And we think that they shouldn’t have to.

That’s why we’re asking Apple to change the unique IDs for each iPhone every month. You would still get relevant ads — but it would be harder for companies to build a profile about you over time.

If you agree with us, will you add your name to Mozilla’s petition?

If Apple makes this change, it won’t just improve the privacy of iPhones — it will send Silicon Valley the message that users want companies to safeguard their privacy by default.

At Mozilla, we’re always fighting for technology that puts users’ privacy first: We publish our annual *Privacy Not Included shopping guide. We urge major retailers not to stock insecure connected devices. And our Mozilla Fellows highlight the consequences of technology that makes publicity, and not privacy, the default.