diff --git a/src/wuttaweb/grids/base.py b/src/wuttaweb/grids/base.py
index 9a6b195..23033a5 100644
--- a/src/wuttaweb/grids/base.py
+++ b/src/wuttaweb/grids/base.py
@@ -578,7 +578,8 @@ class Grid:
                 if key in sorters:
                     continue
                 prop = getattr(self.model_class, key, None)
-                if prop and isinstance(prop.property, orm.ColumnProperty):
+                if (prop and hasattr(prop, 'property')
+                    and isinstance(prop.property, orm.ColumnProperty)):
                     sorters[prop.key] = self.make_sorter(prop)
 
         return sorters