Detection of superhumps in the cataclysmic variable V378 Peg (PG 2337+300)

► We detected the optical oscillation with a period of 3.238 h in the cataclysmic variable V378 Peg. ► This oscillation is unstable both in amplitude and in phase with random phase changes within 10-20% of the period. ► Because of its instability we attribute this oscillation to superhumps. ► V378 Peg shows no outburst typical of dwarf novae and appears as a nova-like variable. ► Hence, the detected superhumps are permanent superhumps, but not common superhumps observed in SU UMa stars.