The wetting behavior of liquid metal was studied for the Al-Sn system with particular reference to low Sn concentrations. It was shown that for Sn concentrations below 5 wt-%, liquid grain boundary films break up into separate inclusions, the wetting angle of which increases with decreasing inclusion size. Possible explanations for this phenomenon are discussed, and it is concluded that the wetting angle is not a fixed constant according solely to Young's equation, but that a correction factor is required for small inclusions.