diff --git a/src/black/lines.py b/src/black/lines.py
index 37615c473fa..0f24192447d 100644
--- a/src/black/lines.py
+++ b/src/black/lines.py
@@ -684,7 +684,8 @@ def _maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
                 return 0, 1
             return before, 1
 
-        # In preview mode, always allow blank lines, except right before a function docstring
+        # In preview mode, always allow blank lines, except right before a function
+        # docstring
         is_empty_first_line_ok = (
             Preview.allow_empty_first_line_in_block in current_line.mode
             and (