2 files changed, 7 insertions, 0 deletions
diff --git a/actionpack/lib/action_controller/metal/live.rb b/actionpack/lib/action_controller/metal/live.rb
index d1734f2138..3c1325cdb4 100644
--- a/actionpack/lib/action_controller/metal/live.rb
+++ b/actionpack/lib/action_controller/metal/live.rb
@@ -78,6 +78,11 @@ module ActionController # :nodoc:
         super(status, header, body)
       end
 
+      def commit!
+        headers.freeze
+        super
+      end
+
       private
 
       def build_buffer(response, body)
diff --git a/actionpack/test/dispatch/live_response_test.rb b/actionpack/test/dispatch/live_response_test.rb
index d17d516a0b..87a6b1383d 100644
--- a/actionpack/test/dispatch/live_response_test.rb
+++ b/actionpack/test/dispatch/live_response_test.rb
@@ -44,6 +44,7 @@ module ActionController
       def test_headers_cannot_be_written_after_write
         @response.stream.write 'omg'
 
+        assert @response.headers.frozen?
         e = assert_raises(ActionDispatch::IllegalStateError) do
           @response.headers['Content-Length'] = "zomg"
         end
@@ -54,6 +55,7 @@ module ActionController
       def test_headers_cannot_be_written_after_close
         @response.stream.close
 
+        assert @response.headers.frozen?
         e = assert_raises(ActionDispatch::IllegalStateError) do
           @response.headers['Content-Length'] = "zomg"
         end