Fitbit, the fitness tracker maker that filed for an IPO worth up to $100 million earlier this month, has an unexpected legal hurdle to overcome: a lawsuit from rival company Jawbone, which claims Fitbit and a group of its former employees stole its trade secrets.

In a filing submitted to the Superior Court in San Francisco, California, on Tuesday, Jawbone accused Fitbit of “clandestine efforts to steal talent, trade secrets and intellectual property from its chief competitor, Jawbone.”

The filing, posted online by the New York Times, names five former employees and accuses them of stealing info on Jawbone’s business plans and products and handing them over to Fitbit where they were subsequently hired.

Jawbone says other former employees were involved, but it doesn’t yet know their names. It is seeking financial damages as well as asking the court to stop the former employees of disclosing any further trade secrets.

“As the pioneer and leader in the connected health and fitness market, Fitbit has no need to take information from Jawbone or any other company,” Fitbit responded in a statement Wednesday. “We are unaware of any confidential or proprietary information of Jawbone in our possession and we intend to vigorously defend against these allegations.”

Jawbone produces a line of fitness trackers called UP, helping users track their weight, eating and sleep habits. Fitbit‘s eponymous fitness trackers perform a similar functionality.

In a filing with regulators, Fitbit said it has sold almost 21 million devices since 2011, but more than half of those sales were made in 2014. The company reported $745.4 million in revenue in 2014, almost triple its total from the previous year. That pace continued into 2015, as its sales more than tripled to $336.8 million in the first quarter.

Additional reporting by the Associated Press

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