3 files changed, 2 insertions, 28 deletions
diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index cc042b5ac3..48ba1518e0 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,10 +1,5 @@
 ## Rails 4.0.0 (unreleased) ##
 
-*   Added `NullMimeTypeObject` class. This  allows to use html?, xml?, json?..etc when
-    the `format` of `request` is unknown.
-   
-    *Angelo  Capilleri*
-
 *   `date_select` helper accepts `with_css_classes: true` to add css classes similar with type
     of generated select tags.
 
diff --git a/actionpack/lib/action_dispatch/http/mime_type.rb b/actionpack/lib/action_dispatch/http/mime_type.rb
index 5ee6f2056e..3d560518e1 100644
--- a/actionpack/lib/action_dispatch/http/mime_type.rb
+++ b/actionpack/lib/action_dispatch/http/mime_type.rb
@@ -153,7 +153,7 @@ module Mime
       end
 
       def lookup_by_extension(extension)
-        EXTENSION_LOOKUP[extension.to_s] || NullMimeTypeObject.new
+        EXTENSION_LOOKUP[extension.to_s]
       end
 
       # Registers an alias that's not used on mime type lookup, but can be referenced directly. Especially useful for
@@ -301,17 +301,6 @@ module Mime
         method.to_s.ends_with? '?'
       end
   end
-
-  class NullMimeTypeObject
-    private
-    def method_missing(method, *args)
-      if method.to_s.ends_with? '?'
-        false
-      else
-        super
-      end
-    end
-  end
 end
 
 require 'action_dispatch/http/mime_types'
diff --git a/actionpack/test/dispatch/request_test.rb b/actionpack/test/dispatch/request_test.rb
index b3466faffb..e2964f9071 100644
--- a/actionpack/test/dispatch/request_test.rb
+++ b/actionpack/test/dispatch/request_test.rb
@@ -590,17 +590,7 @@ class RequestTest < ActiveSupport::TestCase
 
     request = stub_request
     request.expects(:parameters).at_least_once.returns({ :format => :unknown })
-    assert_instance_of Mime::NullMimeTypeObject , request.format
-  end
-
-
-  test "format is not nil with unknown format" do
-    request = stub_request
-    request.expects(:parameters).at_least_once.returns({ format: :hello })
-    assert_equal request.format.html?, false
-    assert_equal request.format.xml?, false
-    assert_equal request.format.json?, false
-    assert !request.format.html?
+    assert request.formats.empty?
   end
 
   test "formats with xhr request" do