Apple supplier Foxconn is quadrupling daily bonuses provided to workers in order to retain enough employees to continue assembling iPhones, reports Reuters. In November, Foxconn is offering workers at its Zhengzhou plant a bonus of 400 yuan per day ($55), up 4x from the normal 100 yuan bonus.

Employees who work for more than 25 days can get a maximum bonus of 5,000 yuan for the month, up from 1,500 yuan, and those who put in “full effort” can earn a bonus of over 15,000 yuan. Most workers earn between 3,000 and 4,000 yuan on a monthly basis.

Foxconn employs around 200,000 people in Zhengzhou, the factory that is used for most of its iPhone production. Foxconn is responsible for assembling around 70 percent of the iPhones that Apple sells, and it has been struggling to keep employees on site due to COVID lockdowns.

Because of China’s zero-COVID policy, Chinese cities are required to quickly quell outbreaks through restrictions, and with COVID spreading in Zhengzhou, workers have wanted to return home to avoid being stuck at the factory should there be a more stringent lockdown. Workers have also been unhappy with restrictions at the factory, such as the closure of the dine-in cafeteria, and a shortage of supplies that caused a panic.

Employee issues at the Zhengzhou plant could cause ‌iPhone‌ output to fall as much as 30 percent, though Foxconn is working to mitigate the supply issues by offering the bonuses and ramping up production at another factory in Shenzhen.