diff --git a/actionpack/lib/action_controller/session/cookie_store.rb b/actionpack/lib/action_controller/session/cookie_store.rb
index 3d21e812eae1..2fcee56fda30 100644
--- a/actionpack/lib/action_controller/session/cookie_store.rb
+++ b/actionpack/lib/action_controller/session/cookie_store.rb
@@ -114,11 +114,8 @@ def call(env)
           end
 
           cookie = build_cookie(@key, cookie.merge(options))
-          unless headers[HTTP_SET_COOKIE].blank?
-            headers[HTTP_SET_COOKIE] << "\n#{cookie}"
-          else
-            headers[HTTP_SET_COOKIE] = cookie
-          end
+          headers[HTTP_SET_COOKIE] = [] if headers[HTTP_SET_COOKIE].blank?
+          headers[HTTP_SET_COOKIE] << cookie
         end
 
         [status, headers, body]
diff --git a/actionpack/test/controller/session/cookie_store_test.rb b/actionpack/test/controller/session/cookie_store_test.rb
index 5ef8eec8bdde..26d56890d4af 100644
--- a/actionpack/test/controller/session/cookie_store_test.rb
+++ b/actionpack/test/controller/session/cookie_store_test.rb
@@ -44,6 +44,12 @@ def raise_data_overflow
       head :ok
     end
 
+    def set_session_value_and_cookie
+      cookies["foo"] = "bar"
+      session[:foo] = "bar"
+      render :text => Rack::Utils.escape(Verifier.generate(session.to_hash))
+    end
+
     def rescue_action(e) raise end
   end
 
@@ -96,7 +102,7 @@ def test_setting_session_value
     with_test_route_set do
       get '/set_session_value'
       assert_response :success
-      assert_equal "_myapp_session=#{response.body}; path=/; HttpOnly",
+      assert_equal ["_myapp_session=#{response.body}; path=/; HttpOnly"],
         headers['Set-Cookie']
    end
   end
@@ -164,7 +170,7 @@ def test_setting_session_value_after_session_reset
       get '/set_session_value'
       assert_response :success
       session_payload = response.body
-      assert_equal "_myapp_session=#{response.body}; path=/; HttpOnly",
+      assert_equal ["_myapp_session=#{response.body}; path=/; HttpOnly"],
         headers['Set-Cookie']
 
       get '/call_reset_session'
@@ -193,6 +199,14 @@ def test_persistent_session_id
     end
   end
 
+  def test_setting_session_value_and_cookie
+    with_test_route_set do
+      get '/set_session_value_and_cookie'
+      assert_response :success
+      assert_equal({"_myapp_session" => response.body, "foo" => "bar"}, cookies)
+    end
+  end
+
   private
     def with_test_route_set
       with_routing do |set|