diff --git a/Lib/test/test_wsgiref.py b/Lib/test/test_wsgiref.py
index 438d8ec..0b1a637 100755
--- a/Lib/test/test_wsgiref.py
+++ b/Lib/test/test_wsgiref.py
@@ -9,7 +9,9 @@
 from wsgiref.simple_server import make_server
 from io import StringIO, BytesIO, BufferedReader
 from socketserver import BaseServer
-import re, sys
+import os
+import re
+import sys
 
 from test import support
 
@@ -444,6 +446,11 @@
 class ErrorHandler(BaseCGIHandler):
     """Simple handler subclass for testing BaseHandler"""
 
+    # BaseHandler records the OS environment at import time, but envvars
+    # might have been changed later by other tests, which trips up
+    # HandlerTests.testEnviron().
+    os_environ = dict(os.environ.items())
+
     def __init__(self,**kw):
         setup_testing_defaults(kw)
         BaseCGIHandler.__init__(