diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
index bdc7ef62943a28..4609ebc10672d2 100644
--- a/Lib/test/pickletester.py
+++ b/Lib/test/pickletester.py
@@ -15,6 +15,7 @@
 import types
 import unittest
 import weakref
+from contextlib import contextmanager
 from textwrap import dedent
 from http.cookies import SimpleCookie
 
@@ -152,6 +153,17 @@ def __getinitargs__(self):
 __main__.E = E
 E.__module__ = "__main__"
 
+@contextmanager
+def fake_main_module():
+    real_main = sys.modules.get("__main__")
+    fake_main = types.ModuleType("__main__")
+
+    sys.modules["__main__"] = fake_main
+    try:
+        yield
+    finally:
+        sys.modules["__main__"] = real_main
+
 # Simple mutable object.
 class Object:
     pass
@@ -2287,10 +2299,12 @@ def test_nested_lookup_error(self):
         obj.__module__ = None
         for proto in protocols:
             with self.subTest(proto=proto):
-                with self.assertRaises(pickle.PicklingError) as cm:
-                    self.dumps(obj, proto)
+                with fake_main_module():
+                    with self.assertRaises(pickle.PicklingError) as cm:
+                        self.dumps(obj, proto)
                 self.assertEqual(str(cm.exception),
-                    f"Can't pickle {obj!r}: it's not found as __main__.AbstractPickleTests.spam")
+                    f"Can't pickle {obj!r}: "
+                    "it's not found as __main__.AbstractPickleTests.spam")
                 self.assertEqual(str(cm.exception.__context__),
                     "module '__main__' has no attribute 'AbstractPickleTests'")
 
@@ -2304,16 +2318,19 @@ def test_wrong_object_lookup_error(self):
                 with self.assertRaises(pickle.PicklingError) as cm:
                     self.dumps(obj, proto)
                 self.assertEqual(str(cm.exception),
-                    f"Can't pickle {obj!r}: it's not the same object as {__name__}.AbstractPickleTests")
+                    f"Can't pickle {obj!r}: "
+                    f"it's not the same object as {__name__}.AbstractPickleTests")
                 self.assertIsNone(cm.exception.__context__)
 
         obj.__module__ = None
         for proto in protocols:
             with self.subTest(proto=proto):
-                with self.assertRaises(pickle.PicklingError) as cm:
-                    self.dumps(obj, proto)
+                with fake_main_module():
+                    with self.assertRaises(pickle.PicklingError) as cm:
+                        self.dumps(obj, proto)
                 self.assertEqual(str(cm.exception),
-                    f"Can't pickle {obj!r}: it's not found as __main__.AbstractPickleTests")
+                    f"Can't pickle {obj!r}: "
+                    "it's not found as __main__.AbstractPickleTests")
                 self.assertEqual(str(cm.exception.__context__),
                     "module '__main__' has no attribute 'AbstractPickleTests'")