A New York City Department of Education employee has been punished for mining bitcoin at work.

Mining bitcoin—or the process of validating blockchain transactions and releasing new coins—takes a serious amount of computing power. A single bitcoin transaction now requires more energy than an entire American household uses in a day. In 2017, it's extremely difficult to mine the world's most popular cryptocurrency without investing in expensive and space-hogging hardware.

In order to get around these limitations, one entrepreneurial man decided he would simply mine bitcoin at NYC's Department of Education, where he's worked as a computer systems manager for over a decade. Unfortunately for Vladimir Ilyayev, he was caught and fined four vacation days (worth an estimated $611) by the New York City Conflicts of Interest Board (COIB), according to a recently published disposition.