diff --git a/trnsystor/deck.py b/trnsystor/deck.py
index f4a1fb0..3c8f723 100644
--- a/trnsystor/deck.py
+++ b/trnsystor/deck.py
@@ -290,7 +290,7 @@ def to_file(self, path_or_buf, encoding=None, mode="w"):
         if path_or_buf is None:
             return formatter.path_or_buf.getvalue()
 
-        return None
+        return path_or_buf
 
     def save(self, path_or_buf, encoding=None, mode="w"):
         """Save Deck to file.