diff --git a/docs/reference/reference_classes.rst b/docs/reference/reference_classes.rst
index dc0805d..d99057e 100644
--- a/docs/reference/reference_classes.rst
+++ b/docs/reference/reference_classes.rst
@@ -44,6 +44,7 @@
 .. autoclass:: black.UnformattedLines
     :show-inheritance:
     :members:
+    :special-members: __str__
 
 :class:`Visitor`
 ----------------