The uncertainty of heat-capacity determinations by means of differential scanning calorimeters (DSCs) is essentially given by the heat-transfer conditions between heater, sample and surroundings. Changes in heat transfer become apparent as an offset between the initial and final isotherms. This offset is a quantitative measure of the systematic uncertainty of a heat-capacity determination and can, therefore, be applied to correct the measurement result. Offsets of approx. 5% yield systematic deviations of up to 1%.