diff --git a/graphviz/saving.py b/graphviz/saving.py
index c8a9e03195..0a95e8f523 100644
--- a/graphviz/saving.py
+++ b/graphviz/saving.py
@@ -17,7 +17,7 @@
 class Save(encoding.Encoding, base.Base):
     """Save DOT source lines to file."""
 
-    directory: str = ''
+    directory: typing.Union[str, bytes] = ''
 
     _default_extension = _defaults.DEFAULT_SOURCE_EXTENSION