diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index 908e292d968ef..1fb5bb94b2c8a 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -235,9 +235,9 @@ impl<'a, I: Iterator- >> Iterator for CodeBlocks<'_, 'a, I> {
return Some(Event::Html(
format!(
"",
- format!(" class=\"language-{}\"", lang),
+ lang,
Escape(&text),
)
.into(),