In this talk I will present a integrability-based conjecture for the three-point functions of single-trace operators in planar N=4 super-Yang-Mills theory at finite coupling, focusing on the case where two operators are protected. This proposal is based on the hexagon representation for structure constants of long operators, which we completed to incorporate operators of any length using data from the TBA/QSC formalism. I will then, using the small spin and classical limit, be able to verifying recent two-loop results for structure constants in string theory and generalising them to operators with arbitrary R-charges.