When engineer Seth Vargo found that a company using his open-source code worked with US Immigration and Customs Enforcement (ICE), he pulled the code off GitHub. The company, enterprise software maker Chef, found that, without the code, its business ground to a halt.

Vargo had worked for the Seattle-based company, but he didn’t know about the contract with ICE until tech writer Shanley Kane tweeted about it on Monday. ICE, which was formed under the presidency of George W. Bush in 2003, has stirred protests as it ratcheted up deportation and family separation policies under President Donald Trump. ICE uses Chef for IT functions.

hey @chef can you please provide a statement on your $100k contract with ICE, as documented here: https://t.co/x1awrUmVEt — shanley (@shanley) September 16, 2019

Vargo reached out to Chef executives to better understand their rationale for the ICE contract, but got no response for three days. “It became apparent that they had no interest in acknowledging their partnership with ICE — the organization best known for tearing apart families and locking children in cages,” Vargo wrote in a text conversation with The Verge.

This morning, he decided to pull the open-source project off GitHub. He knew the company would notice, but he was surprised to find out it relied on his code so heavily that it began experiencing significant downtimes at once. It took Chef engineers about an hour and a half to get the systems back up and running — by 12 PM PT the software was restored.

“As software engineers, we have to abide by some sort of moral compass,” Vargo wrote. “When I learned that my code was being used for purposes that I personally perceive as evil, I felt an obligation to prevent that.”

Vargo’s actions are part of a larger swell of activism among tech employees who have begun protesting company policies and government contracts that go against their own moral code. In August, 1,500 Google employees signed a petition asking the company to stop working with ICE and US Customs and Border Protection (CBP) after a contract with CBP came to light. When Vargo yanked his code, Chef employees voiced their support.

props to the Google Engineer who yanked code from Chef for working with ICE. You've made my job harder today, but I really don't mind. — marea rosa (@smrt_fasizmu) September 19, 2019

In a letter to employees, Chef CEO Barry Crist acknowledged employees might feel uncomfortable with the contract:

I do not believe that it is appropriate, practical, or within our mission to examine specific government projects with the purpose of selecting which U.S. agencies we should or should not do business. My goal is to continue growing Chef as a company that transcends numerous U.S. presidential administrations.

In an email to The Verge, Crist added “To the best of our knowledge, our software is not being used to facilitate the separation of families at the border.” The company plans to continue working with the agency until their contract with ICE ends in 2020.

Update September 21st, 10:45AM ET: Added comments from Chef CEO Barry Crist.