According to a report from Bloomberg, Apple has filed petitions with the USPTO to challenge four of Qualcomm’s patents in their ongoing bitter patent battle. Apple are hoping to have the patents in question canceled to help with their ongoing infringement lawsuit that Qualcomm filed in 2017.

The next step in the process is for the Patent Trial and Appeal Board to review the petitions from Apple and give Qualcomm the opportunity to make its case. The board will then make a “preliminary” decision as to the likelihood of Apple winning its case, and make a final decision after a year.

The patents being challenged involve ways to automatically focus a digital camera; a device that functions as both a phone and personal digital assistant; touch-sensitive displays; and circuit memory. Christie Thoene, a Qualcomm spokeswoman, said the company had no comment.

Apple has challenged the validity 398 patents thus far, though its success rate in doing so is unclear.