A method of repairing a crack in a component comprising a base material, in particular in a gas turbine blade, a suspension, which comprises a carrier liquid and at least one solid in the form of nanoparticles of the same material as the base material, being applied to the location to be repaired. A heat treatment of the component is carried out, the solid in the form of nanoparticles being melted and a bond with the base material being formed. During the heat treatment, the component is exposed to a thermal shock, in which a maximum temperature which corresponds to the melting temperature of the nanoparticles is reached. The nano size of the particles in the suspension causes a lowering of the melting point of these particles to take place, so that the structure of the base material does not change even at the melting temperature of the nanoparticles.