diff --git a/music21/tree/verticality.py b/music21/tree/verticality.py
index 0d325554f..ce0d29bec 100644
--- a/music21/tree/verticality.py
+++ b/music21/tree/verticality.py
@@ -875,7 +875,7 @@ def conditionalAdd(ts, n: note.Note) -> None:
                 continue
             el = timeSpan.element
             if isinstance(el, chord.ChordBase):
-                firstNoteElement: note.Note|None = None
+                firstNoteElement: note.Note | None = None
                 for subEl in el:
                     if isinstance(subEl, note.Note):
                         firstNoteElement = subEl