The effects of soft-errors in flip-flops remains a concern in large designs. There exist many radiation hardened flip-flops, however, these are custom cells and not available to all designers. In this paper, we explore a technique for the mitigation of flip-flop soft-errors through an optimization of the temporal vulnerability factor (TVF). By selectively inserting delay on the input or output of flip-flops, the probability of propagation of single event upsets (SEUs) can be minimized. The selection of where to insert the added delay is formulated as a linear programming problem. In this way, the flip-flop soft-error rate (SER) can be minimized subject to overhead constraints.