The current-voltage characteristics can vary significantly between individual microfabricated tips in as-fabricated arrays of cold cathodes. Such emission nonuniformity is undesirable in device applications. We have shown that in situ tip self-heating by the emitted electron current can be used to make the current-voltage characteristics of microfabricated field emitter tips nearly identical to one another. The improved emission uniformity will allow for more reliable array operation at increased electron emission current densities.