Carl Icahn isn’t ready to walk away from his malpractice battle with Wachtell, Lipton, Rosen & Katz. On Monday, Icahn-controlled CVR Energy Inc. filed a notice of appeal of a ruling last month dismissing the company’s malpractice case against Wachtell and two of its partners.

In a 2013 lawsuit, CVR alleged that Wachtell and partners Benjamin Roth and Andrew Brownstein failed to explain the terms of the company’s fee agreement with two investment banks that CVR hired in an unsuccessful attempt to fend off Icahn’s takeover bid. The company wants Wachtell to reimburse it for the $36 million it paid the banks, as well as for Wachtell’s $6 million fee.