A system and method for hardening a Null Convention Logic (NCL) circuit against Single Event Upset (SEU) is presented. Placing a resistive element into a feedback loop of the NCL circuit may harden the NCL circuit. A bypass element may be placed in parallel with the resistive element to increase the latching speed of the hardened NCL circuit. Additionally, replacing transistors in an input driver, the feedback loop, and an inverter with transistor stacks, which may include two or more transistors connected in series, may harden the NCL circuit. Further, two NCL gates may be cross-coupled to harden the NCL circuit.