diff --git a/script/test/20220201/MultiRegionScan.py b/script/test/20220201/MultiRegionScan.py
index 17f59823..1266b3dd 100644
--- a/script/test/20220201/MultiRegionScan.py
+++ b/script/test/20220201/MultiRegionScan.py
@@ -245,7 +245,7 @@ class ImageReader(ReadonlyRegisterBase, ReadonlyRegisterMatrix):
         ny = Scienta.slices.read()
         return ny
 
-class SimpleDeviceReader(Readable):
+class SimpleDeviceReader(ReadonlyRegisterBase):
     """
     pseudo-device class to read out another device once per region.