diff --git a/lib/rx/null_api.rb b/lib/rx/null_api.rb
index f248bee..5723219 100644
--- a/lib/rx/null_api.rb
+++ b/lib/rx/null_api.rb
@@ -2,8 +2,9 @@ module RX
 
   class NullAPI
 
-    def method_missing(m)
+    def method_missing(*args)
       # whatever
+      return true if args[0] == :end
       nil
     end
   end