One constructs an explicit set of independent infinitesimal deformations of a two-dimensional cusp singularity and one formulates the conjecture that this spans the whole space \(T^ 1\) of infinitesimal deformations. As a corollary one gets Karras' result about non-rigidity of such singularities (due to Freitag and Kiehl, cusp singularities of dimension greater than two are rigid). Later, the author has been able to prove the conjecture and thus an explicit description of \(T^ 1\) is now available.