An apparatus for hardening logic circuitry against a Single-Event-Effect condition and for providing immunity to an overshoot and undershoot condition is provided. The apparatus includes undershoot-blocking and overshoot-blocking modules that are configured to be coupled to overshoot-insensitive and undershoot-insensitive nodes of the logic circuitry, respectively. The undershoot-blocking module is operable to (i) receive from a first node of the logic circuitry a first signal event having a undershoot condition impressed thereon, and (ii) block it from passing to the overshoot-insensitive node. The overshoot-blocking module is operable to (i) receive from the first node a second signal event having an overshoot condition impressed thereon, and (ii) block it from passing to the undershoot-insensitive node. As such, further propagation of the overshoot and undershoot conditions are prevented.