Earth-sized exoplanets in the habitable zone around M-dwarfs are often tidally locked to the host star. This has the effect that one hemisphere always faces the star, while the other remains in darkness. An exomoon in an M-dwarf system does not face this challenge, as it is tidally locked to the planet and it would receive light for both hemispheres. Martínez-Rodríguez et al. studied the possibility of exomoons around planets that orbit M-dwarfs in the habitable zone. While they found 33 exoplanets from earlier studies that lie in the habitable zone, only four could host Moon- to Titan-mass exomoons for timescales longer than 0.8 Gyr (CD–23 1056 b, Ross 1003 b, IL Aquarii b and c). For this mass range the exomoons could probably not hold onto their atmosphere. The researchers increased the mass for the exomoons and found that exomoons with the mass of Mars around IL Aquarii b and c could be stable on timescales above the Hubble time. The CHEOPS mission could detect exomoons around the brightest M-dwarfs or ESPRESSO could detect the Rossiter–McLaughlin effect caused by the exomoons. Both methods require a transiting exoplanet, which is not the case for these four candidates.