diff --git a/actionpack/lib/action_dispatch/http/upload.rb b/actionpack/lib/action_dispatch/http/upload.rb
index 538bcfdcd7885..540e11a4a0703 100644
--- a/actionpack/lib/action_dispatch/http/upload.rb
+++ b/actionpack/lib/action_dispatch/http/upload.rb
@@ -28,6 +28,7 @@ def initialize(hash) # :nodoc:
         raise(ArgumentError, ':tempfile is required') unless @tempfile
 
         @original_filename = hash[:filename]
+        @original_filename &&= @original_filename.encode "UTF-8"
         @content_type      = hash[:type]
         @headers           = hash[:head]
       end
diff --git a/actionpack/test/dispatch/uploaded_file_test.rb b/actionpack/test/dispatch/uploaded_file_test.rb
index 9f6381f118d33..55ebbd514359b 100644
--- a/actionpack/test/dispatch/uploaded_file_test.rb
+++ b/actionpack/test/dispatch/uploaded_file_test.rb
@@ -18,6 +18,12 @@ def test_filename_should_be_in_utf_8
       assert_equal "UTF-8", uf.original_filename.encoding.to_s
     end
 
+    def test_filename_should_always_be_in_utf_8
+      uf = Http::UploadedFile.new(:filename => 'foo'.encode(Encoding::SHIFT_JIS),
+                                  :tempfile => Object.new)
+      assert_equal "UTF-8", uf.original_filename.encoding.to_s
+    end
+
     def test_content_type
       uf = Http::UploadedFile.new(:type => 'foo', :tempfile => Object.new)
       assert_equal 'foo', uf.content_type