Digital transaction watermarking today is a widely accepted mechanism in multimedia security. One major threat on transaction watermarking are collusion attacks. Here multiple individualized copies of the work are mixed to produce a counterfeited or undetectable watermark. One common countermeasure is the usage of so-called fingerprints. Theoretical fingerprint approaches do not consider the inaccuracy of the detection process of watermarking algorithms. In this work we show how an existing fingerprint code can be optimized with respect to code length in order to collaborate with a watermarking algorithm to provide a maximum of reliability with a minimum of payload.