Expressions for the piezoelectric corrections to the second‐ and third‐order coupling parametersK2andK3in cubic, rhombohedral, tetragonal, and orthorhombic crystalline structures are presented. The corrections depend on the linear and nonlinear dielectric constants, second‐ and third‐order piezoelectric moduli (which are related to the elasto‐optic, electrostrictive, and the electroacoustic coefficients). The corrections are estimated for the cases of crystalline quartz and lithium niobate.