Is your iPhone or iPad telling you that iOS 11.4.1 is ready to download? On Monday, it's officially rolling out -- and there may be more than meets the eye to this particular update.

While it appears to merely be a set of bugfixes, an Apple support page confirms it includes a brand-new, much talked-about feature: a USB Restricted Mode to keep police departments, governments and bad actors from breaking into your iPhone.

Apple characterizes the new mode as closing a security hole, not a way to lock out the cops, but either way, it shuts off data to new USB accessories that plug into your iPhone's Lightning port if it's been more than an hour since you last unlocked your iPhone. 

That way, it'll presumably prevent people from using devices like the infamous GrayKey to unlock your handset. In April, Motherboard reported that law enforcement agencies across the US had purchased a GrayKey, which cost upwards of $15,000. 

Generally, your phone chargers should still work, and so should USB accessories you plug in before the 1-hour timeout expires, according to Apple's support site. But Apple warns that some chargers might not -- presumably ones that are looking for a data connection before they fire up.

The new feature's on by default, according to The Verge, but you can flip a "USB Accessories" switch in your Face ID & Passcode (or Touch ID & Passcode) menu to override the 1-hour timeout.

Other tiny highlights of the iOS 11.4.1 update include a bugfix for Find My AirPods and syncing with Exchange servers for email, contacts and notes.

Apple didn't immediately respond to a request for comment.

Update, 12:11p.m. PT: Added link and context from Apple's official support page.