The Boston Globe website is closing off a hole in its paywall by preventing visitors who aren't logged in from reading articles in a browser's private mode.

"You're using a browser set to private or incognito mode" is the message given to BostonGlobe.com visitors who click on articles in private mode. "To continue reading articles in this mode, please log in to your Globe account." People who aren't already Globe subscribers are urged to subscribe.

Like other news sites, the Globe limits the number of articles people can read without a subscription. Until the recent change, Globe website visitors could read more articles for free by switching to private or incognito mode. (You can still get a new supply of free articles by clearing the Globe's cookies from your browser.)

We noticed the change this morning, and it turns out people on Reddit started talking about it yesterday. (They aren't happy about it.)

Newspapers closing holes in their paywalls is nothing new—it is a business, after all, relying on a mix of advertising and subscription revenue. But this particular method of enforcing a paywall prevents nonsubscribers from getting a little extra privacy in their Web browsing.

Incognito mode has plenty of limitations, to be sure. The mode prevents browsers from saving your browsing history and Web cache and disables storage of cookies. But as Google notes, private mode in browsers like Chrome won't stop the websites you visit from seeing that you've visited them. Still, private modes can thwart cross-site tracking, "prevent[ing] companies from tracking your browsing history across multiple sites," as Firefox browser maker Mozilla notes.

Disabling your browser's local storage of data, even if you're not technically using "incognito" mode, will also trigger the anti-private mode message on the Globe website. But you can disable third-party cookies and still view Globe articles in regular mode, as long as you allow the websites you visit to store data.

While you can use BostonGlobe.com in private mode with a subscriber's account, logging in would obviously make it easier for the Globe to keep track of your reading habits if it were inclined to do so.

The Globe policy is a case of "disrespecting user preferences," Electronic Frontier Foundation Senior Staff Technologist Alexei Miagkov told Ars. Miagkov was not aware of any other sites blocking users in private browsing mode.

Logging into the website in private mode puts your privacy at risk, he said. "By logging in you make it easy for them to keep tracking you, to keep building their (advertising) user profiles," he said. "They may also sync their tracking data with their advertising partners whereas if you hadn't logged in, those advertising partners might see a new visitor for every new incognito session."

An unusual policy

The Globe's new policy is different from those imposed by the country's largest papers. The New York Times allows free viewing in private mode. So does USA Today, The Los Angeles Times, The New York Post, Newsday, The Chicago Tribune, The New York Daily News, The Washington Post, The Denver Post, The Houston Chronicle, and The Dallas Morning News. The Wall Street Journal's paywall is fairly hard to defeat but seems to work the same in private and regular mode.

Those are the top 12 newspapers by circulation in the US, according to an Agility PR list that apparently draws from data current as of January 2016. The Globe was 13th. The 14th and 15th names on that list, The Seattle Times and Tampa Bay Times, also both allow free reading in private mode. Getting an up-to-date, accurate comparison of newspaper circulation, including print and online subscriptions, is difficult. The Alliance for Audited Media stopped issuing such reports in 2014. But comparing the Globe to the other papers on the Agility PR list at least gives a sense of how unusual the Globe's new policy is.

The Globe's anti-private mode policy is not enforced on Boston.com, a free news site that's owned by the Globe but doesn't offer the Globe's premium articles.

We contacted the Globe today and will update this article if the paper answers our questions.