diff --git a/myst_parser/mdit_to_docutils/base.py b/myst_parser/mdit_to_docutils/base.py
index 3b5e15da..e7cd70ff 100644
--- a/myst_parser/mdit_to_docutils/base.py
+++ b/myst_parser/mdit_to_docutils/base.py
@@ -289,9 +289,7 @@ def _render_finalise(self) -> None:
             )
             substitution_node.source = self.document["source"]
             substitution_node["names"].append(key)
-            self.document.note_substitution_def(
-                substitution_node, key
-            )
+            self.document.note_substitution_def(substitution_node, key)
 
     def nested_render_text(
         self,