An Illinois music director hit a wrong note last month when he allegedly poured oil over music equipment and stairs inside his high school as an end-of-year prank.

Michael Madonia, 56, the former band director at Thornton Fractional South High School in Lansing, resigned from his job shortly after the May 14 incident, but was charged Monday with a misdemeanor offense of reckless conduct, reported.

School officials did not immediately alert authorities, but determined that a police investigation was warranted, the paper reported. Parents and students had appealed to the District 215 School Board to defend Madonia’s character, reported.

There were no injuries in the incident, but Madonia was seen on security video pouring the oil, the report said.