diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 32f4193..91d8f61 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -550,7 +550,9 @@ module ActionDispatch
           end
 
           dispatcher = route.app
-          dispatcher = dispatcher.app while dispatcher.is_a?(Mapper::Constraints)
+          while dispatcher.is_a?(Mapper::Constraints)            
+            dispatcher = dispatcher.call(env).first == 404 ? nil : dispatcher.app 
+          end
 
           if dispatcher.is_a?(Dispatcher) && dispatcher.controller(params, false)
             dispatcher.prepare_params!(params)
diff --git a/actionpack/test/dispatch/routing_test.rb b/actionpack/test/dispatch/routing_test.rb
index 0ac8c24..2ab0fe7 100644
--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -80,6 +80,11 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
 
       match "/projects/status(.:format)"
 
+      constraints(lambda {|req| false }) do
+        get 'terms' => "terms#special"
+      end
+      get 'terms' => "terms#default"
+
       constraints(:ip => /192\.168\.1\.\d\d\d/) do
         get 'admin' => "queenbee#index"
       end
@@ -1447,6 +1452,13 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
     end
   end
 
+  def test_assert_recognizes_with_constraints
+    with_test_routes do
+      @routes = Routes
+      assert_recognizes({:controller => "terms", :action => "default"}, "/terms")
+    end
+  end
+
   def test_resource_new_actions
     with_test_routes do
       assert_equal '/replies/new/preview', preview_new_reply_path