It’s an awkward case for Google. Intellectual Ventures, a firm partly backed by the Internet giant, sued Motorola Mobility Holdings Inc. for patent infringement Thursday, just as Google is working on purchasing the mobile phone maker.

Google announced in August its decision to acquire Motorola Mobility for $12.5 billion, obtaining 17,000 patents that will “supercharge” Google’s Android mobile phone software, the company said in a statement.

Intellectual Ventures, which has a reputation in the Silicon Valley as being one of the worst offenders of patent trolling, acquired the six patents at the center of the suit against Motorola in the past decade, according to Bloomberg.

The company said it approached Motorola Mobility about licensing its inventions in January, but failed to reach an agreement. In the suit, Intellectual Ventures claimed 18 Motorola Mobility products infringed the patents.

“Intellectual Ventures has successfully signed licensing agreements with many of the top handset manufacturers in the world, and has been in discussion with Motorola Mobility for some time,” wrote Chief Litigation Counsel Melissa Finocchio on the company website. “We have a responsibility to our current customers and our investors to defend our intellectual property rights.”

According to the complaint, the company is seeking a trial and unspecified damages.