In a blog post Thursday, WhatsApp announced an update to its terms and privacy policy, the first in four years. And apart from the rest of the fine print, what sticks out is the fact that one of the world’s most popular messaging services will now start sharing users’ data with its parent company, Facebook.

Not that WhatsApp tried to cover up the red flag. If anything, the announcement, titled “Looking ahead for WhatsApp,” extols the benefits — both to Facebook and for its own users — that will follow as a result of the increased coordination.

“By coordinating more with Facebook, we'll be able to do things like track basic metrics about how often people use our services and better fight spam on WhatsApp. And by connecting your phone number with Facebook’s systems, Facebook can offer better friend suggestions and show you more relevant ads if you have an account with them. For example, you might see an ad from a company you already work with, rather than one from someone you've never heard of.”

WhatsApp was sold to Facebook for $19 billion in 2014, and its CEO John Koum had maintained at the time that the company, which would remain autonomous, would never sell users’ personal information to anyone. Technically, the new development is not selling, but only sharing with the parent company, thereby not violating the stance in letter, but in spirit, it comes across as violating the trust of its users.

WhatsApp A security message is seen on a Whatsapp screen, April 6, 2016. Photo: REUTERS/Thomas White

Once users accept WhatsApp’s new policy update, the changes will kick in. However, the company insists that “nothing you share on WhatsApp, including your messages, photos, and account information, will be shared onto Facebook or any of our other family of apps for others to see, and nothing you post on those apps will be shared on WhatsApp for others to see.”

If users don’t want their phone numbers and other analytics data shared with Facebook, they can choose to opt out.

There are two ways to choose not to share your WhatsApp information with Facebook. One is before you click on the “Agree” button for the updated terms and conditions. Choosing to read more about them takes you to a screen where you can uncheck a box that asks permission to share your data with Facebook.

But if you are one of those people who don’t read the text before hitting “Agree,” it’s still not too late. You can open your app, go to Settings > Account > Share my account info and uncheck the box. However, keep in mind that the second method works for only 30 days after accepting the updated terms.

If you are not a Facebook user, this change doesn’t affect you at all.