Make no mistake about who Microsoft sides with in the case of Apple versus FBI.

Microsoft msft president and chief legal officer Brad Smith said at a congressional hearing on Thursday that his company “wholeheartedly” supports Apple’s aapl refusal to assist the FBI in unlocking a terrorist’s iPhone. “We at Microsoft support Apple and will be filing an amicus brief next week,” he said.

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The tech exec apparently whipped out an early 20th century adding machine to illustrate his point, the Seattle Times reports. “We do not believe that courts should seek to resolve issues of 21st century technology with a law that was written in the era of the adding machine,” he said, alluding to the All Writs Act, which is the basis of the FBI’s case.

The Redmond, Wash.-based computing giant joins a number of companies and business leaders that have shown support for Apple’s objection to helping law enforcement break into an iPhone owned by one of the San Bernardino, Calif. shooters. Top tech execs such as Google’s goog Sundar Pichai and Facebook-owned fb WhatsApp’s Jan Koum have made public statements in favor of Apple CEO Tim Cook’s stance.

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Previously, the only hint at Microsoft’s position came last week when CEO Satya Nadella retweeted a link Smith posted to Twitter. The link led to a statement from the industry group Reform Government Surveillance that objects to encryption “backdoors.” (Microsoft co-founder Bill Gates recently walked back from statements that seemed to endorse the FBI’s position.)

Smith’s latest statements came at a hearing over cross-border data transfers. Apple recently backed Microsoft in its legal battle over the since-replaced Safe Harbor rules that governed transatlantic transfers; now Microsoft appears to be returning the favor.

James Comey, director of the FBI, and Bruce Sewell, Apple senior vice president and general counsel, are scheduled to testify before Congress on March 1. The hearing will concern encryption issues.