Abstract This paper presents a single-event-upset tolerant latch design based on a redundant structure featuring four storage nodes (i.e. Quatro). The reference structure manifests single node upset issues when either of the two internal nodes is hit and observes a positive transient afterwards. Two OFF-state transistors are added to those two internal pull-up paths, suppressing positive transient. Simulation and experimental data demonstrate that the proposed design has smaller cross section and higher upset threshold than the reference design.