diff --git a/src/Pluf/HTTP/Response.php b/src/Pluf/HTTP/Response.php
index 850703c..0b5dfdb 100644
--- a/src/Pluf/HTTP/Response.php
+++ b/src/Pluf/HTTP/Response.php
@@ -156,8 +156,9 @@ class Pluf_HTTP_Response
             }
             foreach ($this->cookies as $cookie => $data) {
                 // name, data, expiration, path, domain, secure, http only
-                setcookie($cookie, $data, 
-                          time()+31536000, 
+                $expire = (null == $data) ? time()-31536000 : time()+31536000;
+                $data = (null == $data) ? '' : $data;
+                setcookie($cookie, $data, $expire,
                           Pluf::f('cookie_path', '/'), 
                           Pluf::f('cookie_domain', null), 
                           Pluf::f('cookie_secure', false), 
diff --git a/src/Pluf/Middleware/Session.php b/src/Pluf/Middleware/Session.php
index 8d3fb54..c0337c7 100644
--- a/src/Pluf/Middleware/Session.php
+++ b/src/Pluf/Middleware/Session.php
@@ -128,7 +128,7 @@ class Pluf_Middleware_Session
             $data['Pluf_Session_key'] = $request->session->session_key;
             $response->cookies[$request->session->cookie_name] = self::_encodeData($data);
         }
-        if ($request->session->set_test_cookie != null) {
+        if ($request->session->set_test_cookie != false) {
             $response->cookies[$request->session->test_cookie_name] = $request->session->test_cookie_value;
         }
         return $response;
diff --git a/src/Pluf/Session.php b/src/Pluf/Session.php
index d2e5385..8ff1bac 100644
--- a/src/Pluf/Session.php
+++ b/src/Pluf/Session.php
@@ -160,6 +160,7 @@ class Pluf_Session extends Pluf_Model
 
     public function deleteTestCookie()
     {
-        $this->set_test_cookie = false;
+        $this->set_test_cookie = true;
+        $this->test_cookie_value = null;
     }
 }