diff --git a/scrapy/trunk/scrapy/contrib/downloadermiddleware/cookies.py b/scrapy/trunk/scrapy/contrib/downloadermiddleware/cookies.py
index abec8191a..b5bb3782f 100644
--- a/scrapy/trunk/scrapy/contrib/downloadermiddleware/cookies.py
+++ b/scrapy/trunk/scrapy/contrib/downloadermiddleware/cookies.py
@@ -35,7 +35,7 @@ class CookiesMiddleware(object):
 
     def process_response(self, request, response, spider):
         if request.meta.get('dont_merge_cookies', False):
-            return
+            return response
 
         # extract cookies from Set-Cookie and drop invalid/expired cookies
         jar = self.jars[spider.domain_name]
diff --git a/scrapy/trunk/scrapy/tests/test_downloadermiddleware_cookies.py b/scrapy/trunk/scrapy/tests/test_downloadermiddleware_cookies.py
index f942a9dd6..4451fbd9d 100644
--- a/scrapy/trunk/scrapy/tests/test_downloadermiddleware_cookies.py
+++ b/scrapy/trunk/scrapy/tests/test_downloadermiddleware_cookies.py
@@ -23,65 +23,64 @@ class CookiesMiddlewareTest(TestCase):
     def test_basic(self):
         headers = {'Set-Cookie': 'C1=value1; path=/'}
         req = Request('http://scrapytest.org/')
-        self.mw.process_request(req, self.spider)
-
+        assert self.mw.process_request(req, self.spider) is None
         assert 'Cookie' not in req.headers
 
         res = Response('http://scrapytest.org/', headers=headers)
-        self.mw.process_response(req, res, self.spider)
+        assert self.mw.process_response(req, res, self.spider) is res
 
         #assert res.cookies
 
         req2 = Request('http://scrapytest.org/sub1/')
-        self.mw.process_request(req2, self.spider)
+        assert self.mw.process_request(req2, self.spider) is None
         self.assertEquals(req2.headers.get('Cookie'), "C1=value1")
 
     def test_http_exception(self):
+        req = Request('http://scrapytest.org/')
+        assert self.mw.process_request(req, self.spider) is None
+        assert 'Cookie' not in req.headers
+
         headers = {'Set-Cookie': 'C1=value1; path=/'}
         res = Response('http://scrapytest.org/', headers=headers)
         exc = HttpException(302, 'Redirect', res)
-
-        req = Request('http://scrapytest.org/')
-        self.mw.process_request(req, self.spider)
-        assert 'Cookie' not in req.headers
-
-        self.mw.process_exception(req, exc, self.spider)
+        assert self.mw.process_exception(req, exc, self.spider) is None
         #assert exc.response.cookies
 
         req2 = Request('http://scrapytest.org/sub1/')
-        self.mw.process_request(req2, self.spider)
+        assert self.mw.process_request(req2, self.spider) is None
         self.assertEquals(req2.headers.get('Cookie'), "C1=value1")
 
-
     def test_dont_merge_cookies(self):
         # merge some cookies into jar
         headers = {'Set-Cookie': 'C1=value1; path=/'}
         req = Request('http://scrapytest.org/')
         res = Response('http://scrapytest.org/', headers=headers)
-        self.mw.process_response(req, res, self.spider)
+        assert self.mw.process_response(req, res, self.spider) is res
 
         # test Cookie header is not seted to request
         req = Request('http://scrapytest.org/dontmerge', meta={'dont_merge_cookies': 1})
-        self.mw.process_request(req, self.spider)
+        assert self.mw.process_request(req, self.spider) is None
         assert 'Cookie' not in req.headers
 
         # check that returned cookies are not merged back to jar
         res = Response('http://scrapytest.org/dontmerge', headers={'Set-Cookie': 'dont=mergeme; path=/'})
-        self.mw.process_response(req, res, self.spider)
+        assert self.mw.process_response(req, res, self.spider) is res
+
         req = Request('http://scrapytest.org/mergeme')
-        self.mw.process_request(req, self.spider)
+        assert self.mw.process_request(req, self.spider) is None
         self.assertEquals(req.headers.get('Cookie'), 'C1=value1')
 
     def test_merge_request_cookies(self):
         req = Request('http://scrapytest.org/', cookies={'galleta': 'salada'})
-        self.mw.process_request(req, self.spider)
+        assert self.mw.process_request(req, self.spider) is None
         self.assertEquals(req.headers.get('Cookie'), 'galleta=salada')
 
         headers = {'Set-Cookie': 'C1=value1; path=/'}
         res = Response('http://scrapytest.org/', headers=headers)
-        self.mw.process_response(req, res, self.spider)
+        assert self.mw.process_response(req, res, self.spider) is res
+
         req2 = Request('http://scrapytest.org/sub1/')
-        self.mw.process_request(req2, self.spider)
+        assert self.mw.process_request(req2, self.spider) is None
         self.assertEquals(req2.headers.get('Cookie'), "C1=value1; galleta=salada")