diff --git a/tests/test_downloadermiddleware_httpproxy.py b/tests/test_downloadermiddleware_httpproxy.py
index 81d6cc335..7c97bf32a 100644
--- a/tests/test_downloadermiddleware_httpproxy.py
+++ b/tests/test_downloadermiddleware_httpproxy.py
@@ -123,11 +123,7 @@ class TestHttpProxyMiddleware(TestCase):
 
     def test_no_proxy(self):
         os.environ['http_proxy'] = 'https://proxy.for.http:3128'
-        os.environ['no_proxy'] = '/var/run/docker.sock'
         mw = HttpProxyMiddleware()
-        # '/var/run/docker.sock' may be used by the user for
-        # no_proxy value but is not parseable and should be skipped
-        assert 'no' not in mw.proxies
 
         os.environ['no_proxy'] = '*'
         req = Request('http://noproxy.com')
@@ -149,3 +145,10 @@ class TestHttpProxyMiddleware(TestCase):
         req = Request('http://noproxy.com', meta={'proxy': 'http://proxy.com'})
         assert mw.process_request(req, spider) is None
         self.assertEqual(req.meta, {'proxy': 'http://proxy.com'})
+
+    def test_no_proxy_invalid_values(self):
+        os.environ['no_proxy'] = '/var/run/docker.sock'
+        mw = HttpProxyMiddleware()
+        # '/var/run/docker.sock' may be used by the user for
+        # no_proxy value but is not parseable and should be skipped
+        assert 'no' not in mw.proxies