This paper deals with the problem of assigning operators to jobs, within a free assignment-changing mode, in a job-shop environment subject to a fixed processing sequence of the jobs. We seek an assignment of operators that minimizes the maximum lateness. Within this model, a job needs an operator during the entire duration of its processing. We show that the problem is 𝒩𝒫-hard when the number of operators is arbitrary and exhibit polynomial time algorithms for the cases involving one and two operators, respectively.