This was followed in 1780 by two supplementary volumes to Steevens's version of Dr Johnson's Shakespeare, partly consisting of observations on the history of the Elizabethan stage, and of the text of doubtful plays; and this again, in 1783, by an appendix volume. His refusal to alter some of his notes to Isaac Reed's edition of 1785, which disagreed with Steevens's, resulted in a quarrel with the latter. Malone was also a central figure in the refutation of the claim that the Ireland Shakespeare forgeries were authentic works of the playwright, which many contemporary academics had believed.
