diff --git a/saqc/core/core.py b/saqc/core/core.py
index 5e0c0cf80308eefcf20529a08e281a038d0c546e..acc0ae15c9c7ac595c4880e3030dd467212a3255 100644
--- a/saqc/core/core.py
+++ b/saqc/core/core.py
@@ -247,7 +247,7 @@ class SaQC:
 
             ctrl_kws = FuncCtrl(
                 masking=FUNC_MAP[func_name]["masking"],
-                to_mask=to_mask or self._to_mask,
+                to_mask=self._to_mask if to_mask is None else to_mask,
                 plot=plot,
                 inplace=inplace,
                 )