diff --git a/src/escpos/escpos.py b/src/escpos/escpos.py
index d7cef4f..be2f815 100644
--- a/src/escpos/escpos.py
+++ b/src/escpos/escpos.py
@@ -955,8 +955,8 @@ class Escpos(object):
         height: Optional[int] = 1,
         density: Optional[int] = 9,
         invert: Optional[bool] = False,
-        smooth: bool = False,
-        flip: bool = False,
+        smooth: Optional[bool] = False,
+        flip: Optional[bool] = False,
         double_width: Optional[bool] = False,
         double_height: Optional[bool] = False,
         custom_size: Optional[bool] = False,