diff --git a/spacy/tokens/_serialize.py b/spacy/tokens/_serialize.py
index 0a5fd0c59..192067ed4 100644
--- a/spacy/tokens/_serialize.py
+++ b/spacy/tokens/_serialize.py
@@ -50,7 +50,7 @@ class DocBin:
         self,
         attrs: Iterable[str] = ALL_ATTRS,
         store_user_data: bool = False,
-        docs=Iterable[Doc],
+        docs: Iterable[Doc] = tuple(),
     ) -> None:
         """Create a DocBin object to hold serialized annotations.