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]