diff --git a/rdflib/plugins/serializers/turtle.py b/rdflib/plugins/serializers/turtle.py
index 32b4b90608..e594d04f5e 100644
--- a/rdflib/plugins/serializers/turtle.py
+++ b/rdflib/plugins/serializers/turtle.py
@@ -230,13 +230,15 @@ def reset(self):
     def serialize(
         self,
         stream: BufferedIOBase,
-        base: Optional[str],
-        encoding: Optional[str],
+        base: Optional[str] = None,
+        encoding: Optional[str] = None,
         spacious: Optional[bool] = None,
         **args
     ):
         self.reset()
-        self.stream = TextIOWrapper(stream, encoding, errors="replace", write_through=True)
+        self.stream = TextIOWrapper(
+            stream, encoding, errors="replace", write_through=True
+        )
         # self.encoding = encoding
         # if base is given here, use that, if not and a base is set for the graph use that
         if base is not None: