diff --git a/lib/http/cookie.rb b/lib/http/cookie.rb
index f32a923..a4129ba 100644
--- a/lib/http/cookie.rb
+++ b/lib/http/cookie.rb
@@ -344,9 +344,9 @@ class HTTP::Cookie
     end
   end
 
-  def expired?
+  def expired?(time = Time.now)
     return false unless @expires
-    Time.now > @expires
+    time > @expires
   end
 
   def expire
diff --git a/test/test_http_cookie.rb b/test/test_http_cookie.rb
index ef8489b..9cbf874 100644
--- a/test/test_http_cookie.rb
+++ b/test/test_http_cookie.rb
@@ -451,6 +451,8 @@ class TestHTTPCookie < Test::Unit::TestCase
     cookie = HTTP::Cookie.new(cookie_values)
 
     assert_equal false, cookie.expired?
+    assert_equal true, cookie.expired?(cookie.expires + 1)
+    assert_equal false, cookie.expired?(cookie.expires - 1)
     cookie.expire
     assert_equal true, cookie.expired?
   end