In two studies it is demonstrated that, in the short-term, slot machine gambling increases self-control strength in problem gamblers. In Study 1 (N = 180), participants were randomly assigned to either play slot machines or engage in a control task (word anagrams) for 15 min. Subsequent self-control strength was measured via persistence on an impossible tracing task. Replicating Bergen et al. (J Gambl Stud, doi:10.1007/s10899-011-9274-9, 2011), control condition participants categorized as problem gamblers persisted for less time than did lower gambling risk participants. However, in the slot machine condition, there were no significant differences in persistence amongst participants as a function of their gambling classification. Moreover, problem gambling participants in the slot machine condition persisted at the impossible tracing task longer than did problem gambling participants in the control condition. Study 2 (N = 209) systematically replicated Study 1. All participants initially completed two tasks known to deplete self-control strength and a different control condition (math problems) was used. Study 2 results were highly similar to those of Study 1. The results of the studies have implications for the helping professions. Specifically, helping professionals should be aware that problem gamblers might seek out gambling as a means of increasing self-control strength.