Last week, some OnePlus 5 owners discovered that their phone would reboot when trying to dial emergency services. OnePlus quickly fixed that bug, and now the company has explained what happened.

OnePlus says that the OnePlus 5’s bug with emergency service calls was due to a modem memory usage issue. Here’s the company’s full explanation of the bug:

“The source of this issue was related to a modem memory usage issue that triggered a reboot. This reboot was a random occurrence for some users on VoLTE network where OTDOA protocol was triggered when placing an emergency call.”

OnePlus says that only some OnePlus 5 units were affected, and the company adds that it has worked with Qualcomm to fix this bug globally.

Being unable to contact emergency services is a huge deal, even if only some OnePlus 5 units were affected by this bug. The good news is that the issue was resolved quickly, with OnePlus pushing out a fix within a couple of days of the problem being discovered.