Organisers of the Oscars will continue working with accountancy firm PricewaterhouseCoopers despite the best picture mess at last month's ceremony.
The Academy said PwC had taken responsibility for the "unacceptable" mistake which saw La La Land wrongly announced as the award winner instead of Moonlight.
In a letter to members, Academy President Cheryl Boone Isaacs said new rules will mean electronic devices are banned backstage at next year's show.
Boone Isaacs said: "From the night of the ceremony through today, PwC has taken full responsibility for the mistake.
"After a thorough review, including an extensive presentation of revised protocols and ambitious controls, the Board has decided to continue working with PwC."
Boone Isaacs said PwC US chairman Tim Ryan would now take a "greater oversight role" at future ceremonies.
An on-site PwC team at the Oscars will now include a third person with knowledge of award winners who will sit in the control room with the show's director throughout the event, she added.
Cullinan and fellow PwC accountant Martha Ruiz were told they would never work at the Oscars again following the most high-profile error in the show's history.
PwC took responsibility for the shambles, saying that Cullinan and Ruiz made "a series of mistakes" and failed to follow established backstage protocols.
Cullinan tweeted a photo of La La Land actress Emma Stone from backstage, minutes before handing presenters Beatty and Faye Dunaway the card for Best Actress in a leading role, rather than Best Picture.
Boone Isaacs said Cullinan's distraction caused the error.