Response-time models are of increasing interest in educational and psychological testing. This paper focuses on the lognormal model for response times (van der Linden, 2006), which is one of the most popular response-time models, and suggests a simple person-fit statistic for the model. The distribution of the statistic under the null hypothesis of no misfit is proved to be a chi-squared distribution. A simulation study and a real data example demonstrate the usefulness of the suggested statistic. [This paper was published in "Journal of Educational Measurement" v55 n4 p457-476 2018 (EJ1198338).]