3D and free-viewpoint video has been slowly adopting a solid representation, such as using meshes and point-clouds. Among other characteristics, meshes provide direct surface representation, while point-cloud processing requires less computation. Points in the cloud are minimally represented by their geometry (3D position) and color. A common point-cloud geometry compression method is the octree representation, which acts on individual frames and can be further compressed by entropy encoding. This paper presents a lossless intra-frame compression method for point-cloud geometry, which uses the octree structure to provide better contexts for entropy coding. Results show that the proposed solution offers state-of-the-art performance, with an average rate reduction of 29% compared to the octree representation.