Guaranteeing the correct system behaviour in safety-critical computer-based systems is a challenging issue due to transient faults. This has been demonstrated considering the effects of faults in memory elements containing data structures belonging to a Unix-based Operating System. Elements linked to resource and process synchronization management are particularly critical, thus the need for hardening also the kernel data structures. In order to overcome this vulnerability, a solution is proposed by implementing a triplication technique in the source code of the Linux kernel, aiming at incrementing the robustness of the system. An experimental fault injection analysis has been conducted on the Mutex semaphores to evaluate its effectiveness. The proposed approach successfully detected and corrected the noxious effects generated by single faults in the system with a limited performance overhead.