All it takes is two characters from the alphabet of the Indian language Telugu to crash an array of Apple devices.

If one of the two symbols is sent to a texting app on an iPhone, iPad, Mac, or even Apple Watch, the software immediately crashes. In many cases, it needs to be reinstalled. The bug becomes still more destructive when sent to iMessage, as it will cause the whole device to crash. This is all because of the default font Apple uses.

“The reason of the crash is the San Francisco font itself, when it tries to render division by zero,” Andrew Frost the CEO of Aloha Browser, a software company that first spotted the bug, tells Inverse. “Apps that use different fonts are totally safe.”

What’s going on under the hood is actually pretty simple to understand. The San Francisco font Apple uses doesn’t contain either of these symbols, so a device using the font is essentially looking for a symbol that doesn’t exist. It’s just as brain-breaking for Apple’s software as it would be trying to divide a number by zero, as Frost mentioned.

Aloha Browser software engineers first spotted these detrimental symbols on February 12 and reported it to Open Radar, an open-source bug tracker. The company later discovered the symbol they reported was in fact a combination of two Telugu characters.

“It looks like it works like Chinese — when you type [a] few letters, there is only one you see on the screen,” explained Frost. “The same [principles] apply with Thai; we have checked them as well, but found no issues.”

Aloha Browser reported the two symbols to Apple, then collaborated with TechCrunch for exclusive coverage of this text bomb — but not before word about the company’s initial report spread.

Italian tech blog Mobile World caught wind of the Open Radar report and proceeded to run a story that mistakenly stated there is only one symbol causing the crashes. Several subsequent stories have repeated this error.

Many publications have tested the bug on third party apps. According to TechCrunch, it crashed Mail, Twitter, Messages, Slack, Instagram, Facebook, and Jumpcut.

At the time of writing, Apple has not made an official statement regarding this problem, and the time frame for a fix is unknown.

There’s reason to get this sorted quickly: Until it’s fixed, a malicious actor could spam these symbols across social media platforms, leading to the mass crashing of apps and Apple devices.