Oculus VR, the virtual reality unit of Facebook Inc., are facing a patent infringement lawsuit with a smaller competitor Techno View IP inc. The California-based technology licensing firm allege Oculus infringed a 3D-imaging patent for the Rift headset, owned by the VR headset maker ImmersiON-VRelia.

According to the complaint filed in federal court in Delaware, ImmersiON-VRelia, which has offices in Spain and California, agreed to let Techno View litigate the patent on its behalf.

The lawsuit comes as Facebook weighs its options following a $500 million verdict in an unrelated lawsuit brought over its VR technology by video game developer ZeniMax Media Inc. A Dallas federal jury in February found Oculus used copyrighted computer code developed by video game designer John Carmack while employed at ZeniMax.

Lawyers for Oculus and Facebook have said they will seek to have the verdict set aside.