We propose three fault-tolerant methods for a new lightweight block cipher SIMON, which has the potential to be a hardware-efficient security primitive for embedded systems. As a single fault in the encryption (decryption) process can completely change the ciphertext (received plaintext), it is critical to ensure the reliability of encryption and decryption modules. We explore double-modular redundancy (DMR), reverse function, and a parity check code combined with a non-linear compensation function (EPC) to detect faults in SIMON. The proposed three fault-tolerant methods were implemented in iterative and pipelined SIMON architectures. The corresponding hardware cost, power consumption, and fault detection failure rate were assessed. Simulation results show that EPC-SIMON consumes the less area and power than DMR-SIMON and Reversed-SIMON but yields a higher fault detection failure rate as the number of concurrent faults increases. Our experiments also show that the fault-detection failure rates of different methods upon faults in round and key schedule functions of SIMON are not consistent.