Many IT workers worry their positions will become obsolete as changes in hardware, software, and computing tasks outstrip their skills. A former contractor for Siemens concocted a remedy for that—plant logic bombs in projects he designed that caused them to periodically malfunction. Then wait for a call to come fix things.

On Monday, David A. Tinley, a 62-year-old from Harrison City, Pennsylvania, was sentenced to six months in prison and a fine of $7,500 in the scheme. The sentence came five months after he pleaded guilty to a charge of intentional damage to a protected computer. Tinley was a contract employee for Siemens Corporation at its Monroeville, Pennsylvania, location.

According to a charging document filed in US District Court for the Western District of Pennsylvania, the logic bombs Tinley surreptitiously planted into his projects caused them to malfunction after a certain preset amount of time. Because Siemens managers were unaware of the logic bombs and didn’t know the cause of the malfunctions, they would call Tinley and ask him to fix the misbehaving projects. The scheme ran from 2014 to 2016.

Tinley will be under supervised release for two years following his prison term. He will also pay restitution. The parties in the case stipulated a total loss amount of $42,262.50. Tinley faced as much as 10 years in prison and a $250,000 fine.