diff --git a/lib/plsql/pipelined_function.rb b/lib/plsql/pipelined_function.rb
index bc54ede4..aac0da4f 100644
--- a/lib/plsql/pipelined_function.rb
+++ b/lib/plsql/pipelined_function.rb
@@ -71,5 +71,7 @@ def exec(*args, &block)
       call = PipelinedFunctionCall.new(self, args)
       call.exec(&block)
     end
+
+    private :ensure_tmp_tables_created
   end
 end
\ No newline at end of file