Mylan—the pharmaceutical company infamous for raising the price of EpiPens—is in hot water with the Food and Drug Administration. This time, the dust-up is related to the quality control practices at one of the company’s drug facilities making antiretroviral therapies (ARVs) used to treat HIV, Reuters reports.

In a letter to Mylan, the FDA outlined several violations at the facility, based in Maharashtra, India, and warned Mylan to shape up. Specifically, the FDA said that investigators found that facility employees inexplicably invalidated quality control data that showed that drug batches didn’t meet standards. The agency also claimed that employees didn’t bother trying to investigate those failures or prevent them from reoccurring.

“Your quality system does not adequately ensure the accuracy and integrity of data to support the safety, effectiveness, and quality of the drugs you manufacture,” the FDA wrote. The letter was dated April 3, but it was released by the agency Tuesday.

An FDA inspection in September revealed that from January 1 to June 30, 2016 employees at the facility had invalidated 101 out of 139 quality control test reports that showed drug batches failed standards. But the FDA said that employees didn’t properly follow up to figure out what the problems were and correct them.

In cases where employees did investigate problems, the FDA was unimpressed by the findings. “You attributed numerous incidents to power interruptions, connectivity problems (disconnection of the Ethernet or power cord), and instrument malfunctions,” the FDA noted. But “you could not explain why these events occurred with frequency in your laboratory, nor had you undertaken a comprehensive investigation into the problem or sought to correct it and prevent its recurrence.”

The FDA warned that until Mylan gets its act together—and submits data that proves it—the agency may hold up drug approvals that Mylan has in the FDA’s pipeline.

A spokesperson for Mylan was reported as saying that the company is "working closely with FDA to respond to and address the issues raised in the letter as comprehensively and expeditiously as possible.”

The facility is one of nine that Mylan has making ARVs, which ensures a continuous supply even if there are problems at one.