Ever scaling process technology makes embedded systems more vulnerable to soft errors than in the past. One of the generic methods used to fight soft errors is based on duplicating instructions either in the spatial or temporal domain and then comparing the results to see whether they are different. This full duplication based scheme, though effective, is very expensive in terms of performance, power, and memory space. In this paper, we propose an alternate scheme based on loop invariants and present experimental results which show that our approach catches 62% of the errors caught by full duplication, when averaged over all benchmarks tested. In addition, it reduces the execution cycles and memory demand of the full duplication strategy by 80% and 4%, respectively.