diff --git a/docs/extensions/patch_myst_cite.py b/docs/extensions/patch_myst_cite.py
index 3b8afd34a..2d32dc9e9 100644
--- a/docs/extensions/patch_myst_cite.py
+++ b/docs/extensions/patch_myst_cite.py
@@ -29,5 +29,5 @@ def cite_role(  # noqa: PLR0917
     return [node], []
 
 
-def setup(app: Sphinx):
+def setup(app: Sphinx) -> None:
     app.add_role("cite", cite_role, override=True)