diff --git a/lib/http/cookie.rb b/lib/http/cookie.rb
index fb2056e..f32a923 100644
--- a/lib/http/cookie.rb
+++ b/lib/http/cookie.rb
@@ -12,6 +12,8 @@ class HTTP::Cookie
   # Maximum number of bytes per cookie (RFC 6265 6.1 requires 4096 at least)
   MAX_LENGTH = 4096
 
+  UNIX_EPOCH = Time.at(0)
+
   PERSISTENT_PROPERTIES = %w[
     name        value
     domain      for_domain  path
@@ -347,6 +349,11 @@ class HTTP::Cookie
     Time.now > @expires
   end
 
+  def expire
+    @expires = UNIX_EPOCH
+    self
+  end
+
   alias secure? secure
   alias httponly? httponly
   alias session? session
diff --git a/test/test_http_cookie.rb b/test/test_http_cookie.rb
index bf9edba..ef8489b 100644
--- a/test/test_http_cookie.rb
+++ b/test/test_http_cookie.rb
@@ -447,6 +447,14 @@ class TestHTTPCookie < Test::Unit::TestCase
       })
   end
 
+  def test_expiration
+    cookie = HTTP::Cookie.new(cookie_values)
+
+    assert_equal false, cookie.expired?
+    cookie.expire
+    assert_equal true, cookie.expired?
+  end
+
   def test_equal
     assert_not_equal(HTTP::Cookie.new(cookie_values),
       HTTP::Cookie.new(cookie_values(:value => 'bar')))