Neutron diffraction experiments in zero field reveals that the originally sine wave modulated antiferromagnetic structure in UNiAl starts to square up at low temperatures. The squaring up is, however, not completed even at 150 mK, most probably due to competing magnetic interactions. The fact that the magnetic moments are not equal at all the uranium atomic sites is responsible at least partially for the enhanced low temperature specific heat coefficient observed in UNiAl at low temperatures.