diff --git a/test/with_dummyserver/test_no_ssl.py b/test/with_dummyserver/test_no_ssl.py
index e37794d5..a3f837a9 100644
--- a/test/with_dummyserver/test_no_ssl.py
+++ b/test/with_dummyserver/test_no_ssl.py
@@ -8,10 +8,17 @@
 from dummyserver.testcase import (
         HTTPDummyServerTestCase, HTTPSDummyServerTestCase)
 
+import pytest
 import urllib3
 
 
 class TestHTTPWithoutSSL(HTTPDummyServerTestCase, TestWithoutSSL):
+
+    @pytest.mark.skip(reason=(
+        "TestWithoutSSL mutates sys.modules."
+        "This breaks the backend loading code which imports modules at runtime."
+        "See discussion at https://github.com/python-trio/urllib3/pull/42"
+    ))
     def test_simple(self):
         pool = urllib3.HTTPConnectionPool(self.host, self.port)
         self.addCleanup(pool.close)