diff --git a/app/controllers/search_results_controller.rb b/app/controllers/search_results_controller.rb
index 0f54d574..97a59a07 100644
--- a/app/controllers/search_results_controller.rb
+++ b/app/controllers/search_results_controller.rb
@@ -147,7 +147,7 @@ def index
         format.html do
           render :index
         end
-        format.any(:ttl) do
+        format.any(:ttl, :rdf, :nt) do
           head :bad_request
         end
       end