We investigate the impact of the intracluster medium on the weak-lensing shear power spectrum (PS). Using a halo model we find that, compared to the dark matter-only case, baryonic pressure leads to a suppression of the shear PS on the order of a few percent or more for l ≳ 1000. Cooling/cooled baryons and the intergalactic medium can further alter the shear PS. Therefore, the interpretation of future precision weak-lensing data at high multipoles must take into account the effects of baryons.