The concept of $S$-characters of finite groups was introduced by Zhmud as a generalisation of transitive permutation characters. Any non-trivial $S$-character takes a zero value on some group element. By a deep result depending on the classification of finite simple groups a non-trivial transitive permutation character even vanishes on some element of prime power order. We present an example that this does not generalise to $S$-characters, thereby answering a question posed by J.-P. Serre.