diff --git a/src/doc/src/reference/unstable.md b/src/doc/src/reference/unstable.md
index 4850b7082ec..fce26e146c5 100644
--- a/src/doc/src/reference/unstable.md
+++ b/src/doc/src/reference/unstable.md
@@ -1239,10 +1239,10 @@ fn main() {}
 A user may optionally specify a manifest in a `cargo` code fence in a module-level comment, like:
 ````rust
 #!/usr/bin/env -S cargo +nightly -Zscript
-```cargo
+---cargo
 [dependencies]
 clap = { version = "4.2", features = ["derive"] }
-```
+---
 
 use clap::Parser;