diff --git a/mandaye/http.py b/mandaye/http.py
index aca0871..d2855dd 100644
--- a/mandaye/http.py
+++ b/mandaye/http.py
@@ -154,6 +154,10 @@ class HTTPResponse(object):
         self.headers.load_httpmessage(response.headers)
         for setcookie in response.headers.getheaders('set-cookie'):
             try:
+                cookie = Cookie.SimpleCookie("Set-Cookie: %s" % setcookie)
+                cookie = cookie.values()[0]
+                if self.cookies.has_key(cookie.key):
+                    del self.cookies[cookie.key]
                 self.cookies.load("Set-Cookie: %s" % setcookie)
             except Cookie.CookieError:
                 logger.warning("can't parse cookie: %r", setcookie)