Prosecutors frustrated by repeated slapdowns from the judge at Paul Manafort’s trial made a formal written protest Thursday, complaining they were unfairly called out in front of the jury.

U.S. District Court Judge T.S. Ellis sharply dressed down prosecutors on special counsel Robert Mueller’s team Wednesday for allowing an expert witness from the Internal Revenue Service to remain in the courtroom while other witnesses were testifying. Typically, witnesses aren’t supposed to hear anyone else’s testimony in a trial so they don’t influence each other.

In a written motion filed before court convened Thursday, Mueller’s team asked the judge to explain to the jury that the prosecution had done nothing wrong. Indeed, a transcript of the first day of the trial last week shows that prosecutor Uzo Asonye specifically asked that witnesses be excluded “with the exception of our expert and our [FBI] case agent.” The judge and the prosecutor went on to discuss Michael Welch by name and his expertise. And the judge unmistakably approved the exception.

“The Court mistakenly faulted the government for permitting IRS revenue agent Michael Welch, the government’s expert witness, to remain in the courtroom during the proceedings, when in fact on the first day of trial the Court had expressly granted the government’s motion to do so,” prosecutors complained in their motion. “The Court’s reprimand of government counsel suggested to the jury—incorrectly—that the government had acted improperly and in contravention of Court rules. This prejudice should be cured.”

Ellis chastised Asonye in court on Wednesday moments after he called Welch to the stand. “It’s my clear recollection….that I wasn’t admitting experts,” Ellis said. “You need to ask specifically. You’re going to go ahead now, I’m going to permit that, but I want you to remember that.”

Asonye responded that prosecutors would “check the transcript,” but it was their belief that they specifically asked for permission to allow expert witnesses like Welch to remain in the courtroom despite the usual prohibition.

“Well, let me be clear: I don’t care what the transcript says,” Ellis snapped, before backing down a little. “Maybe I made a mistake. But I want you to remember don’t do that again. When I exclude witnesses, I mean everybody. Now, it may be that I didn’t make that clear.”

The judge’s tone suggested he was disturbed by the prosecutors’ actions, although he eventually declared, “It’s not a big deal.”

In their letter, Mueller’s team said that the judge’s action left a “negative impression” of them. “The Court’s sharp reprimand of government counsel in front of the jury on August 8 was…erroneous. And, while mistakes are a natural part of the trial process, the mistake here prejudiced the government,” Mueller’s team wrote, asking Ellis to tell jurors he was mistaken and the prosecution did nothing wrong.

The judge’s slap at the prosecution over the expert witness issue was just the latest in a series of rebukes he’s delivered to Mueller’s squad in recent days over topics ranging from body language to excessive informality to efforts to introduce visual imagery of Manafort’s lavish lifestyle. The prickly exchanges have clearly begun to grate on the prosecution team, which has sometimes protested verbally in court, but did not formally lodge a written objection before Thursday.