diff --git a/tailbone/views/master.py b/tailbone/views/master.py
index 2e7ac147..21a5e58f 100644
--- a/tailbone/views/master.py
+++ b/tailbone/views/master.py
@@ -903,7 +903,7 @@ class MasterView(View):
 
     def valid_employee_uuid(self, node, value):
         if value:
-            model = self.model
+            model = self.app.model
             employee = self.Session.get(model.Employee, value)
             if not employee:
                 node.raise_invalid("Employee not found")
@@ -939,7 +939,7 @@ class MasterView(View):
 
     def valid_vendor_uuid(self, node, value):
         if value:
-            model = self.model
+            model = self.app.model
             vendor = self.Session.get(model.Vendor, value)
             if not vendor:
                 node.raise_invalid("Vendor not found")
@@ -1382,7 +1382,7 @@ class MasterView(View):
         return classes
 
     def make_revisions_grid(self, obj, empty_data=False):
-        model = self.model
+        model = self.app.model
         route_prefix = self.get_route_prefix()
         row_url = lambda txn, i: self.request.route_url(f'{route_prefix}.version',
                                                         uuid=obj.uuid,
@@ -2153,7 +2153,7 @@ class MasterView(View):
         Thread target for executing an object.
         """
         app = self.get_rattail_app()
-        model = self.model
+        model = self.app.model
         session = app.make_session()
         obj = self.get_instance_for_key(key, session)
         user = session.get(model.User, user_uuid)
@@ -2594,7 +2594,7 @@ class MasterView(View):
         """
         # nb. self.Session may differ, so use tailbone.db.Session
         session = Session()
-        model = self.model
+        model = self.app.model
         route_prefix = self.get_route_prefix()
 
         info = session.query(model.TailbonePageHelp)\
@@ -2617,7 +2617,7 @@ class MasterView(View):
         """
         # nb. self.Session may differ, so use tailbone.db.Session
         session = Session()
-        model = self.model
+        model = self.app.model
         route_prefix = self.get_route_prefix()
 
         info = session.query(model.TailbonePageHelp)\
@@ -2639,7 +2639,7 @@ class MasterView(View):
 
         # nb. self.Session may differ, so use tailbone.db.Session
         session = Session()
-        model = self.model
+        model = self.app.model
         route_prefix = self.get_route_prefix()
         schema = colander.Schema()
 
@@ -2673,7 +2673,7 @@ class MasterView(View):
 
         # nb. self.Session may differ, so use tailbone.db.Session
         session = Session()
-        model = self.model
+        model = self.app.model
         route_prefix = self.get_route_prefix()
         schema = colander.Schema()
 
@@ -5541,7 +5541,7 @@ class MasterView(View):
                                   input_file_templates=True,
                                   output_file_templates=True):
         app = self.get_rattail_app()
-        model = self.model
+        model = self.app.model
         names = []
 
         if simple_settings is None:
@@ -6100,7 +6100,7 @@ class MasterView(View):
                         renderer='json')
 
 
-class ViewSupplement(object):
+class ViewSupplement:
     """
     Base class for view "supplements" - which are sort of like plugins
     which can "supplement" certain aspects of the view.
@@ -6127,6 +6127,7 @@ class ViewSupplement(object):
     def __init__(self, master):
         self.master = master
         self.request = master.request
+        self.app = master.app
         self.model = master.model
         self.rattail_config = master.rattail_config
         self.Session = master.Session
@@ -6160,7 +6161,7 @@ class ViewSupplement(object):
         This is accomplished by subjecting the current base query to a
         join, e.g. something like::
 
-           model = self.model
+           model = self.app.model
            query = query.outerjoin(model.MyExtension)
            return query
         """