O'Connor has written four letters to Cyrus so far this month (Oct13), urging the 20 year old to resist "prostituting herself" to the music industry and then attacking the Wrecking Ball hitmaker for mocking her mental health issues.
And now Stevens is taking aim at Cyrus for her poor use of the English language in the lyrics of her song #GetItRight, which appears on her hit new album Bangerz.
Posting his letter on his official website, Stevens writes: "I can't stop listening to #GetItRight (great song, great message, great body), but maybe you need a quick grammar lesson.
"One particular line causes concern: 'I been laying in this bed all night long.' Miley, technically speaking, you've been Lying, not Laying, an irregular verb form that should only be used when there's an object, i.e. 'I been laying my tired booty on this bed all night long'.
"I'm not the best lyricist, but you know what I mean. #Get It Right The Next Time."