diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index 5f5c0d0..8e92a50 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -581,7 +581,7 @@ def test_fatal_error(self):
         not_expected = ('_testcapi',)
         code = textwrap.dedent('''
             import _testcapi, sys
-            sys.module_names = frozenset({"_testcapi"})
+            sys.stdlib_module_names = frozenset({"_testcapi"})
             _testcapi.fatal_error(b"MESSAGE")
         ''')
         self.check_fatal_error(code, expected)
diff --git a/Lib/test/test_faulthandler.py b/Lib/test/test_faulthandler.py
index 02077a6..6486244 100644
--- a/Lib/test/test_faulthandler.py
+++ b/Lib/test/test_faulthandler.py
@@ -336,7 +336,7 @@ def test_dump_ext_modules(self):
             import faulthandler
             import sys
             # Don't filter stdlib module names
-            sys.module_names = frozenset()
+            sys.stdlib_module_names = frozenset()
             faulthandler.enable()
             faulthandler._sigsegv()
             """
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 729b866..c4e0535 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -987,8 +987,8 @@ def test_orig_argv(self):
                          proc)
 
     def test_module_names(self):
-        self.assertIsInstance(sys.module_names, frozenset)
-        for name in sys.module_names:
+        self.assertIsInstance(sys.stdlib_module_names, frozenset)
+        for name in sys.stdlib_module_names:
             self.assertIsInstance(name, str)