A boundary version of the Schwarz lemma for meromorphic functions is investigated. For the function $I^nf(z)=\frac1z+\sum_{k=2}^{\infty}k^nc_{k-2}z^{k-2}$, belonging to the class of $\mathcal W$, we estimate from below the modulus of the angular derivative of the function on the boundary point of the unit disc.