An Arizona teenager was arrested in October and accused of creating malicious code that would make infected iPhones dial 911 and clog the critical emergency line. The code, which prompted thousands of calls to 911, took advantage of a feature in Apple’s iOS mobile operating system that would automatically place calls when users clicked on a link to a telephone number.

The code, allegedly created by 18-year-old Meetkumar Desai, spread on social media to unwitting victims. Desai was charged with four counts of felony computer tampering.

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Apple fixed the automatic-dialing feature in this week’s iOS 10.3 software update, according to The Wall Street Journal. When users download the free update, iOS will now require users to confirm that they want to place a call after clicking on a telephone number link. The fix works both in Apple’s apps, as well as across apps by other developers.

However, people who don’t update to iOS 10.3 are still subject to the prank, which is believed to still be circulating on social media and elsewhere. Users of older iOS versions, therefore, should be careful.

The fix comes just days after another “prank” surfaced that involves Apple and targets emergency calls. When iPhone users say “Hey Siri, 108” into their iPhones, the virtual assistant assumes users want to dial emergency services and automatically places the call. The feature is designed for users in India to get easy access to emergency services; 108 is the 911 of India. Saying 108 in the U.S. apparently dials 911 as a safety measure. But its unclear how Apple could fix that feature, if it in fact plans to do so.