1 files changed, 5 insertions, 1 deletions
diff --git a/actionpack/lib/action_controller/mime_responds.rb b/actionpack/lib/action_controller/mime_responds.rb
index 1dbd8b9e6f..29294476f7 100644
--- a/actionpack/lib/action_controller/mime_responds.rb
+++ b/actionpack/lib/action_controller/mime_responds.rb
@@ -114,7 +114,11 @@ module ActionController #:nodoc:
         @request    = controller.request
         @response   = controller.response
 
-        @mime_type_priority = Array(Mime::Type.lookup_by_extension(@request.parameters[:format]) || @request.accepts)
+        if ActionController::Base.use_accept_header
+          @mime_type_priority = Array(Mime::Type.lookup_by_extension(@request.parameters[:format]) || @request.accepts)
+        else
+          @mime_type_priority = [@request.format]
+        end
 
         @order     = []
         @responses = {}