A cleanup fluid for reducing a viscosity of a residual viscous material in fractures of a hydrocarbon-bearing formation is disclosed. The cleanup fluid includes an acid precursor, the acid precursor operable to trigger an exothermic reaction component and the exothermic reaction component operable to generate heat, where the heat is operable to reduce a viscosity of the residual viscous material to create a reduced viscosity material, the reduced viscosity material operable to flow from the fractures.