diff --git a/Lib/test/test_ipaddress.py b/Lib/test/test_ipaddress.py
index 02028bf..95518af 100644
--- a/Lib/test/test_ipaddress.py
+++ b/Lib/test/test_ipaddress.py
@@ -456,16 +456,16 @@
         assertBadNetmask("1.1.1.1", "pudding")
         assertBadNetmask("1.1.1.1", "::")
 
-
-class InterfaceTestCase_v4(BaseTestCase, NetmaskTestMixin_v4):
-    factory = ipaddress.IPv4Interface
-
     def test_pickle(self):
         self.pickle_test('192.0.2.0/27')
         self.pickle_test('192.0.2.0/31')  # IPV4LENGTH - 1
         self.pickle_test('192.0.2.0')     # IPV4LENGTH
 
 
+class InterfaceTestCase_v4(BaseTestCase, NetmaskTestMixin_v4):
+    factory = ipaddress.IPv4Interface
+
+
 class NetworkTestCase_v4(BaseTestCase, NetmaskTestMixin_v4):
     factory = ipaddress.IPv4Network