Given a Lagrangian two-torus with an attached Lagrangian disk, one can construct a different Lagrangian torus by a procedure called mutation. I will talk about the wall-crossing formula which describes how the enumerative geometry of holomorphic Maslov index 2 disks changes under mutation. I will also mention higher-dimensional mutations, and the wall-crossing formula for them. This is joint work with James Pascaleff.