diff --git a/test/helpers/data_writer_helper.rb b/test/helpers/data_writer_helper.rb
index 24535ac8..76b46f0a 100644
--- a/test/helpers/data_writer_helper.rb
+++ b/test/helpers/data_writer_helper.rb
@@ -150,6 +150,7 @@ def start_synchronized_datawriter_threads
               sleep(0.03)
             end
           ensure
+            @started_callback_cmd << n unless @started # if #stop_and_join is called before first write
             connection.close
           end