A visual secret sharing (VSS) scheme with minimum pixel expansion is proposed to prevent malicious participants from deceiving an honest participant. A VSS scheme encrypts a secret image into pieces referred to as shares where each participant keeps a share so that stacking sufficient number of shares recovers the secret image. A cheat prevention VSS scheme provides another piece for each participant for verifying whether the shares presented by other participants are genuine. The proposed scheme improves the contrast of the recovered image and cheat-prevention functionality by introducing randomness in producing pieces for verification. Experimental results show the effectiveness of the proposed scheme.