1.Institut f╱r Kernphysik, Technische Universit╝t Darmstadt, 64289 Darmstadt, Germany;
2.ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum f╱r Schwerionenforschung GmbH, 64291 Darmstadt, Germany;
3.Institute of High Energy Physics and Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences, Beijing 100049, China;
4.Center for High Energy Physics, Peking University, Beijing 100871, China;
:The quark mass dependence of hadrons is an important input for lattice calculations. We investigate the light quark mass dependence of the binding energy of the X(3872) in a finite box to next-to-leading order in an effective field theory for the X(3872) with perturbative pions (XEFT). At this order, the quark mass dependence is determined by a quark mass-dependent contact interaction in addition to the one-pion exchange. While there is only a moderate sensitivity to the light quark masses in the region up to twice their physical value, the finite volume effects are significant already at box length as large as 20 fm.