The Academy announced on Saturday, the day before Oscar Sunday, that Greg P. Russell’s sound mixing nomination for “13 Hours: The Secret Soldiers of Benghazi” has been revoked for “violation of Academy campaign regulations.” Gary Summers, Jeffrey J. Haboush and Mac Ruth remain sound mixing nominees for the film.

“The decision was prompted by the discovery that Russell had called his fellow members of the Sound Branch during the nominations phase to make them aware of his work on the film, in direct violation of a campaign regulation that prohibits telephone lobbying,” the release said.

“The Board of Governors’ decision to rescind Mr. Russell’s nomination was made after careful consideration,” Academy President Cheryl Boone Isaacs said in a statement. “The Academy takes very seriously the Oscars voting process and anything – no matter how well-intentioned – that may undermine the integrity of that process.”

According to the release, Academy rules state that “contacting Academy members by telephone to promote a film or achievement is expressly forbidden, even if such contact is in the guise of checking to make sure a screener or other mailing was received.”

The decision was made after a vote on Thursday by the Academy’s Board of Governors, upon recommendation by the Sound Branch Executive Committee.

After the decision, the sound mixing nominees for the 2017 Academy Awards are Bernard Gariepy Strobl and Claude La Haye for “Arrival”; Kevin O’Connell, Andy Wright, Robert Mackenzie and Peter Grace for “Hacksaw Ridge”; Andy Nelson, Ai-Ling Lee and Steve A. Morrow for “La La Land”; David Parker, Christopher Scarabosio and Stuart Wilson for “Rogue One: A Star Wars Story”; and Summers, Haboush and Ruth for “13 Hours.”