The short-time expansion of the diffusion coefficient in powers of t1/2 is universally connected to structural parameters of the boundaries restricting the diffusive motion. The t1/2-term is proportional to the surface-to-volume ratio. The t-term is related to permeability and curvature. The short-time expansion can be measured by application of oscillating gradients of long total duration. For oscillating gradients, the inverse of the oscillation frequency becomes the relevant time scale. The purpose of this work is to show that the oscillating gradient approach is blind to the t-term. Thus, the t-term does not bias the determination of the t1/2-term in experiments.