Quantum spin liquids are novel magnetic states in which quantum entanglement suppresses conventional magnetic order. Understanding the effects that stabilise such states is an important aim in condensed-matter physics. We propose to investigate structural disorder in the recently-synthesised quantum spin-liquid candidate YbMgGaO4, in which magnetic Yb(III) layers are separated by disordered Mg(II)/Ga(III) layers. We propose to use neutron pair-distribution function measurements to determine how Mg(II) and Ga(III) occupancies are correlated over short distances, and to reveal possible local distortions of the Yb(III) magnetic layers. These results will help to interpret our low-temperature inelastic neutron-scattering measurements, and to understand how structural disorder affects the quantum spin-liquid state in YbMgGaO4.