2 files changed, 8 insertions, 9 deletions
diff --git a/test/dialect/postgresql/test_compiler.py b/test/dialect/postgresql/test_compiler.py
index 0b56d8987..5ada6f592 100644
--- a/test/dialect/postgresql/test_compiler.py
+++ b/test/dialect/postgresql/test_compiler.py
@@ -41,7 +41,7 @@ from sqlalchemy.dialects.postgresql import TSRANGE
 from sqlalchemy.dialects.postgresql.base import PGDialect
 from sqlalchemy.dialects.postgresql.psycopg2 import PGDialect_psycopg2
 from sqlalchemy.orm import aliased
-from sqlalchemy.orm import mapper
+from sqlalchemy.orm import clear_mappers
 from sqlalchemy.orm import Session
 from sqlalchemy.sql import column
 from sqlalchemy.sql import literal_column
@@ -2728,7 +2728,7 @@ class InsertOnConflictTest(fixtures.TestBase, AssertsCompiledSQL):
         )
 
 
-class DistinctOnTest(fixtures.TestBase, AssertsCompiledSQL):
+class DistinctOnTest(fixtures.MappedTest, AssertsCompiledSQL):
 
     """Test 'DISTINCT' with SQL expression language and orm.Query with
     an emphasis on PG's 'DISTINCT ON' syntax.
@@ -2825,7 +2825,8 @@ class DistinctOnTest(fixtures.TestBase, AssertsCompiledSQL):
         class Foo(object):
             pass
 
-        mapper(Foo, self.table)
+        clear_mappers()
+        self.mapper_registry.map_imperatively(Foo, self.table)
         sess = Session()
         subq = sess.query(Foo).subquery()
 
@@ -2842,7 +2843,7 @@ class DistinctOnTest(fixtures.TestBase, AssertsCompiledSQL):
         class Foo(object):
             pass
 
-        mapper(Foo, self.table)
+        self.mapper_registry.map_imperatively(Foo, self.table)
         a1 = aliased(Foo)
         sess = Session()
         self.assert_compile(
diff --git a/test/dialect/postgresql/test_types.py b/test/dialect/postgresql/test_types.py
index bb8e44876..92641fcc6 100644
--- a/test/dialect/postgresql/test_types.py
+++ b/test/dialect/postgresql/test_types.py
@@ -3034,17 +3034,15 @@ class HStoreRoundTripTest(fixtures.TablesTest):
         )
         self._assert_data([{r"key \"foo\"": r'value \"bar"\ xyz'}], connection)
 
-    def test_orm_round_trip(self, connection):
-        from sqlalchemy import orm
-
+    def test_orm_round_trip(self, registry):
         class Data(object):
             def __init__(self, name, data):
                 self.name = name
                 self.data = data
 
-        orm.mapper(Data, self.tables.data_table)
+        registry.map_imperatively(Data, self.tables.data_table)
 
-        with orm.Session(connection) as s:
+        with fixtures.fixture_session() as s:
             d = Data(
                 name="r1",
                 data={"key1": "value1", "key2": "value2", "key3": "value3"},