William Shakespeare might have been high while writing his famous plays. A new study from researchers in South Africa shows evidence that The Bard might have been smoking cannabis 400 years ago.

The researchers in Pretoria used state-of-the-art forensic technology to examine residue on tobacco pipes found in Shakespeare’s garden. They used a technique called “gas chromatography mass spectrometry,” Francis Thackeray of the University of the Witwatersrand wrote in The Independent.

According to Today.com, the researchers did fing evidence of marijuana-related compounds in the clay bits from the pipes.

While it is true that use of cannabis was common in Elizabethan England, it’s not clear if Shakespeare actually came up with ideas for his plays while high. He did mention a “noted weed” in one of his sonnets, but scholars believe he was referring to clothing, not smoking.

Today.com notes that the findings were actually first published in 2001, but Thackeray re-published them in the hope that they are taken more seriously. When the findings were first published, Shakespeare scholars weren’t impressed and didn’t think marijuana would have influenced the Bard’s work.

“Chemical analyses of residues in early 17th century clay ‘tobacco pipes’ have confirmed that a diversity of plants were smoked in Europe. Literary analyses and chemical science can be mutually beneficial, bringing the arts and the sciences together in an effort to better understand Shakespeare and his contemporaries,” Thackeray wrote in the study.