diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 2df62329411889b..fe5f1c87b0b18c3 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -3194,10 +3194,14 @@ def test_wrong_cert_tls13(self):
             # TLS 1.3 perform client cert exchange after handshake
             s.connect((HOST, server.port))
             try:
-                s.write(b'data')
-                s.read(1000)
-                s.write(b'should have failed already')
-                s.read(1000)
+                written = s.write(b'data')
+                print("write1", written)
+                data = s.read(1000)
+                print("recv1", len(data))
+                written = s.write(b'should have failed already')
+                print("write2", written)
+                data = s.read(1000)
+                print("recv2", len(data))
             except ssl.SSLError as e:
                 if support.verbose:
                     sys.stdout.write("\nSSLError is %r\n" % e)
@@ -3207,13 +3211,7 @@ def test_wrong_cert_tls13(self):
                 if support.verbose:
                     sys.stdout.write("\nsocket.error is %r\n" % e)
             else:
-                if sys.platform == "win32":
-                    self.skipTest(
-                        "Ignoring failed test_wrong_cert_tls13 test case. "
-                        "The test is flaky on Windows, see bpo-43921."
-                    )
-                else:
-                    self.fail("Use of invalid cert should have failed!")
+                self.fail("Use of invalid cert should have failed!")
 
     def test_rude_shutdown(self):
         """A brutal shutdown of an SSL server should raise an OSError
diff --git a/Lib/unittest/result.py b/Lib/unittest/result.py
index ce7468e31481f07..e671b977758bff7 100644
--- a/Lib/unittest/result.py
+++ b/Lib/unittest/result.py
@@ -202,7 +202,7 @@ def _exc_info_to_string(self, err, test):
 
 
     def _is_relevant_tb_level(self, tb):
-        return '__unittest' in tb.tb_frame.f_globals
+        return '__unittest' in (tb.tb_frame.f_globals or {})
 
     def _count_relevant_tb_levels(self, tb):
         length = 0