diff --git a/python/lsst/ip/diffim/detectAndMeasure.py b/python/lsst/ip/diffim/detectAndMeasure.py
index 1c1cbba5..e8374610 100644
--- a/python/lsst/ip/diffim/detectAndMeasure.py
+++ b/python/lsst/ip/diffim/detectAndMeasure.py
@@ -209,6 +209,7 @@ def setDefaults(self):
                                            "base_LocalWcs",
                                            "ext_shapeHSM_HsmSourceMoments",
                                            "ext_shapeHSM_HsmPsfMoments",
+                                           "base_ClassificationSizeExtendedness",
                                            ]
         self.measurement.slots.psfShape = "ext_shapeHSM_HsmPsfMoments"
         self.measurement.slots.shape = "ext_shapeHSM_HsmSourceMoments"