diff --git a/keystone/application_credential/backends/sql.py b/keystone/application_credential/backends/sql.py
index c647fb68a1..057a0fa09e 100644
--- a/keystone/application_credential/backends/sql.py
+++ b/keystone/application_credential/backends/sql.py
@@ -44,11 +44,13 @@ class ApplicationCredentialModel(sql.ModelBase, sql.ModelDictMixin):
     roles = sqlalchemy.orm.relationship(
         'ApplicationCredentialRoleModel',
         backref=sqlalchemy.orm.backref('application_credential'),
-        cascade='all, delete-orphan')
+        cascade='all, delete-orphan',
+        cascade_backrefs=False)
     access_rules = sqlalchemy.orm.relationship(
         'ApplicationCredentialAccessRuleModel',
         backref=sqlalchemy.orm.backref('application_credential'),
-        cascade='all, delete-orphan')
+        cascade='all, delete-orphan',
+        cascade_backrefs=False)
 
 
 class ApplicationCredentialRoleModel(sql.ModelBase, sql.ModelDictMixin):
@@ -78,7 +80,8 @@ class AccessRuleModel(sql.ModelBase, sql.ModelDictMixin):
     )
     application_credential = sqlalchemy.orm.relationship(
         'ApplicationCredentialAccessRuleModel',
-        backref=sqlalchemy.orm.backref('access_rule'))
+        backref=sqlalchemy.orm.backref('access_rule'),
+        cascade_backrefs=False)
 
 
 class ApplicationCredentialAccessRuleModel(sql.ModelBase, sql.ModelDictMixin):
diff --git a/keystone/tests/unit/ksfixtures/warnings.py b/keystone/tests/unit/ksfixtures/warnings.py
index 4a603a5ec3..f02580b7bf 100644
--- a/keystone/tests/unit/ksfixtures/warnings.py
+++ b/keystone/tests/unit/ksfixtures/warnings.py
@@ -79,16 +79,6 @@ class WarningsFixture(fixtures.Fixture):
             category=sqla_exc.SADeprecationWarning,
         )
 
-        # ...but filter everything out until we get around to fixing them
-        # TODO(stephenfin): Fix all of these
-
-        warnings.filterwarnings(
-            'ignore',
-            module='keystone',
-            message=r'".*" object is being merged into a Session along .*',
-            category=sqla_exc.SADeprecationWarning,
-        )
-
         self.addCleanup(self._reset_warning_filters)
 
     def _reset_warning_filters(self):