diff --git a/lib/async/websocket/adapters/rails.rb b/lib/async/websocket/adapters/rails.rb
index 9e635e8..0b6e764 100644
--- a/lib/async/websocket/adapters/rails.rb
+++ b/lib/async/websocket/adapters/rails.rb
@@ -13,7 +13,7 @@ def self.open(request, **options, &block)
 					if response = Rack.open(request.env, **options, &block)
 						::Rack::Response[*response]
 					else
-						::ActionDispatch::Response.new(404, [], [])
+						::ActionDispatch::Response.new(404)
 					end
 				end
 			end