diff --git a/cromulant/args.py b/cromulant/args.py
index 9798d09..8097c59 100644
--- a/cromulant/args.py
+++ b/cromulant/args.py
@@ -9,7 +9,7 @@ from .argspec import ArgSpec
 
 
 class Args:
-    names: Path
+    names: Path | None = None
     images: bool = True
 
     @staticmethod