Many PET scanners nowadays have the possibility to record event-by-event information, known as list mode data. This has the advantage of keeping the data in the highest possible resolution (both temporal and spatial). In most cases, list mode data are then binned into sinogram format before reconstruction. In this paper, we discuss at which stage normalisation factors should be introduced. It is shown that noise is greatly reduced by performing the normalisation after the binning. We illustrate this with acquired and simulated data for the quad HiDAC camera.