diff --git a/Lib/test/test_site.py b/Lib/test/test_site.py
index b32aef1d5da..83252227ec2 100644
--- a/Lib/test/test_site.py
+++ b/Lib/test/test_site.py
@@ -459,7 +459,8 @@ class StartupImportTests(unittest.TestCase):
         # http://bugs.python.org/issue19218>
         collection_mods = {'_collections', 'collections', 'functools',
                            'heapq', 'itertools', 'keyword', 'operator',
-                           'reprlib', 'types', 'weakref'}
+                           'reprlib', 'types', 'weakref'
+                          }.difference(sys.builtin_module_names)
         self.assertFalse(modules.intersection(collection_mods), stderr)
 
 
diff --git a/Misc/NEWS b/Misc/NEWS
index d820400435f..60125712abe 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -255,6 +255,9 @@ Documentation
 Tests
 -----
 
+- Issue #21223: Pass test_site/test_startup_imports when some of the extensions
+  are built as builtins.
+
 - Issue #20635: Added tests for Tk geometry managers.
 
 - Add test case for freeze.