diff --git a/Rakefile b/Rakefile
index 76a56296..4676930b 100644
--- a/Rakefile
+++ b/Rakefile
@@ -14,7 +14,7 @@ task :default => :test
 namespace :warning do
   desc "Treat warning as error"
   task :error do
-    def Warning.warn(*message)
+    def Warning.warn(*message, **)
       super
       raise "Treat warning as error:\n" + message.join("\n")
     end