The pre-peak structure at around 1 Å 1 correspond to peak in the Li-Li partial structure factor. It has been analyzed previously and attributed to Li clustering. It is expected to be pronounced by the large di↵erence in sizes of Li and Cs and K ions, by a factor of 3. Our results show that Cs does not a↵ect this clustering in FLiNaK because of the already large amounts of large K ions.