diff --git a/Lib/test/support/script_helper.py b/Lib/test/support/script_helper.py
index 2627a1ee68a4b5..1e746472ee6348 100644
--- a/Lib/test/support/script_helper.py
+++ b/Lib/test/support/script_helper.py
@@ -67,17 +67,28 @@ def run_python_until_end(*args, **env_vars):
     elif not env_vars and not env_required:
         # ignore Python environment variables
         cmd_line.append('-E')
-    # Need to preserve the original environment, for in-place testing of
-    # shared library builds.
-    env = os.environ.copy()
-    # set TERM='' unless the TERM environment variable is passed explicitly
-    # see issues #11390 and #18300
-    if 'TERM' not in env_vars:
-        env['TERM'] = ''
+
     # But a special flag that can be set to override -- in this case, the
     # caller is responsible to pass the full environment.
     if env_vars.pop('__cleanenv', None):
         env = {}
+        if sys.platform == 'win32':
+            # Windows requires at least the SYSTEMROOT environment variable to
+            # start Python.
+            env['SYSTEMROOT'] = os.environ['SYSTEMROOT']
+
+        # Other interesting environment variables, not copied currently:
+        # COMSPEC, HOME, PATH, TEMP, TMPDIR, TMP.
+    else:
+        # Need to preserve the original environment, for in-place testing of
+        # shared library builds.
+        env = os.environ.copy()
+
+    # set TERM='' unless the TERM environment variable is passed explicitly
+    # see issues #11390 and #18300
+    if 'TERM' not in env_vars:
+        env['TERM'] = ''
+
     env.update(env_vars)
     cmd_line.extend(args)
     proc = subprocess.Popen(cmd_line, stdin=subprocess.PIPE,
diff --git a/Lib/test/test_imaplib.py b/Lib/test/test_imaplib.py
index f451930566833d..fac6b57081283b 100644
--- a/Lib/test/test_imaplib.py
+++ b/Lib/test/test_imaplib.py
@@ -477,7 +477,7 @@ class NewIMAPTests(NewIMAPTestsMixin, unittest.TestCase):
 
 @unittest.skipUnless(ssl, "SSL not available")
 class NewIMAPSSLTests(NewIMAPTestsMixin, unittest.TestCase):
-    imap_class = imaplib.IMAP4_SSL
+    imap_class = IMAP4_SSL
     server_class = SecureTCPServer
 
     def test_ssl_raises(self):