diff --git a/scrapy/http/cookies.py b/scrapy/http/cookies.py
index cc96cf8ac..3e3dff741 100644
--- a/scrapy/http/cookies.py
+++ b/scrapy/http/cookies.py
@@ -29,7 +29,7 @@ class CookieJar(object):
         if not IPV4_RE.search(req_host):
             hosts = potential_domain_matches(req_host)
             if req_host.find(".") == -1:
-                hosts += req_host + ".local"
+                hosts += [req_host + ".local"]
         else:
             hosts = [req_host]
 
diff --git a/tests/test_downloadermiddleware_cookies.py b/tests/test_downloadermiddleware_cookies.py
index ffa3a550c..1ca52ef84 100644
--- a/tests/test_downloadermiddleware_cookies.py
+++ b/tests/test_downloadermiddleware_cookies.py
@@ -8,6 +8,12 @@ from scrapy.contrib.downloadermiddleware.cookies import CookiesMiddleware
 
 class CookiesMiddlewareTest(TestCase):
 
+    def test_local_domain(self):
+        request = Request("http://example-host/", cookies={'currencyCookie': 'USD'})
+        assert self.mw.process_request(request, self.spider) is None
+        assert 'Cookie' in request.headers
+        assert 'currencyCookie' in request.headers['Cookie']
+
     def assertCookieValEqual(self, first, second, msg=None):
         cookievaleq = lambda cv: re.split(';\s*', cv)
         return self.assertEqual(