diff --git a/phoenix_bec/devices/unsupported_legacy/psi_detector_base.py b/phoenix_bec/devices/unsupported_legacy/psi_detector_base.py
index 12a4b37..8744fec 100644
--- a/phoenix_bec/devices/unsupported_legacy/psi_detector_base.py
+++ b/phoenix_bec/devices/unsupported_legacy/psi_detector_base.py
@@ -326,7 +326,7 @@ class PSIDetectorBase(Device):
     (https://bec.readthedocs.io/en/latest/) for more information about device integration.
     """
 
-    custom_prepare_cls = CustomDetectorMixin
+    custom_prepare_cls =        
 
     filepath = Cpt(SetableSignal, value="", kind=Kind.config)
 
@@ -369,7 +369,7 @@ class PSIDetectorBase(Device):
         self.scaninfo = None
         self.filewriter = None
 
-        if not issubclass(self.custom_prepare_cls, CustomPrepare):
+        if not issubclass(self.custom_prepare_cls, CustomDetectorMixin):
             raise BECDeviceBaseError(
                 f"Custom prepare class must be subclass of CustomDetectorMixin, provided: {self.custom_prepare_cls}"
             )