3 files changed, 7 insertions, 3 deletions
diff --git a/bsie/reader/builder.py b/bsie/reader/builder.py
index bce5397..8699e75 100644
--- a/bsie/reader/builder.py
+++ b/bsie/reader/builder.py
@@ -40,7 +40,11 @@ class ReaderBuilder():
     # cached readers
     _cache: typing.Dict[str, base.Reader]
 
-    def __init__(self, kwargs: typing.Dict[str, typing.Dict[str, typing.Any]]):
+    def __init__(
+            self,
+            kwargs: typing.Optional[typing.Dict[str, typing.Dict[str, typing.Any]]] = None):
+        if kwargs is None:
+            kwargs = {}
         self._kwargs = kwargs
         self._cache = {}
 
diff --git a/bsie/reader/chain.py b/bsie/reader/chain.py
index db7c2d5..5e9e0d5 100644
--- a/bsie/reader/chain.py
+++ b/bsie/reader/chain.py
@@ -37,7 +37,7 @@ class ReaderChain(base.Reader, typing.Generic[T_CONTENT]):
     def __init__(
             self,
             subreader_names: typing.Iterable[str],
-            cfg: typing.Any,
+            cfg: typing.Optional[typing.Any] = None,
             ):
         rbuild = builder.ReaderBuilder(cfg)
         children = []
diff --git a/bsie/reader/image/__init__.py b/bsie/reader/image/__init__.py
index b7587e7..1f290b5 100644
--- a/bsie/reader/image/__init__.py
+++ b/bsie/reader/image/__init__.py
@@ -31,7 +31,7 @@ __all__: typing.Sequence[str] = (
 class Image(chain.ReaderChain[PIL.Image.Image]): # pylint: disable=too-few-public-methods
     """Read an image file."""
 
-    def __init__(self, cfg):
+    def __init__(self, cfg: typing.Optional[typing.Any] = None):
         super().__init__(_FILE_FORMAT_READERS, cfg)
 
 ## EOF ##