3 files changed, 9 insertions, 7 deletions
diff --git a/actionpack/lib/action_controller/metal/live.rb b/actionpack/lib/action_controller/metal/live.rb
index 69583f8ab4..667c7f87ca 100644
--- a/actionpack/lib/action_controller/metal/live.rb
+++ b/actionpack/lib/action_controller/metal/live.rb
@@ -145,8 +145,8 @@ module ActionController
 
       def write(string)
         unless @response.committed?
-          @response.headers["Cache-Control"] = "no-cache"
-          @response.headers.delete "Content-Length"
+          @response.set_header "Cache-Control", "no-cache"
+          @response.delete_header "Content-Length"
         end
 
         super
diff --git a/actionpack/lib/action_controller/metal/mime_responds.rb b/actionpack/lib/action_controller/metal/mime_responds.rb
index e62da0fa70..88a4818c16 100644
--- a/actionpack/lib/action_controller/metal/mime_responds.rb
+++ b/actionpack/lib/action_controller/metal/mime_responds.rb
@@ -191,7 +191,7 @@ module ActionController #:nodoc:
 
       if format = collector.negotiate_format(request)
         _process_format(format)
-        _set_content_type _get_content_type format
+        _set_rendered_content_type format
         response = collector.response
         response ? response.call : render({})
       else
diff --git a/actionpack/lib/action_controller/metal/rendering.rb b/actionpack/lib/action_controller/metal/rendering.rb
index c8934b367f..4214399b6f 100644
--- a/actionpack/lib/action_controller/metal/rendering.rb
+++ b/actionpack/lib/action_controller/metal/rendering.rb
@@ -56,12 +56,14 @@ module ActionController
       nil
     end
 
-    def _get_content_type(rendered_format)
-      self.content_type || super
+    def _set_html_content_type
+      self.content_type = Mime::HTML.to_s
     end
 
-    def _set_content_type(format)
-      self.content_type = format
+    def _set_rendered_content_type(format)
+      unless response.content_type
+        self.content_type = format.to_s
+      end
     end
 
     # Normalize arguments by catching blocks and setting them on :update.