diff --git a/doc/howto/use-opam-alongside-dune-package-management.rst b/doc/howto/use-opam-alongside-dune-package-management.rst
index 00cbf5a2fc3..cc35b22319d 100644
--- a/doc/howto/use-opam-alongside-dune-package-management.rst
+++ b/doc/howto/use-opam-alongside-dune-package-management.rst
@@ -16,7 +16,7 @@ following contents:
 
 .. code:: dune
 
-   (lang dune 3.20)
+   (lang dune 3.21)
 
    (pkg disabled)
 
@@ -31,7 +31,7 @@ file:
 
 .. code:: dune
 
-   (lang dune 3.20)
+   (lang dune 3.21)
 
    (pkg enabled)