diff --git a/test/support/config_histories.rb b/test/support/config_histories.rb
index cda6d9b..7b69956 100644
--- a/test/support/config_histories.rb
+++ b/test/support/config_histories.rb
@@ -17,7 +17,7 @@ module ConfigHistories
             port 24224
           </source>
         CONFIG
-        new_config = <<-CONFIG
+        new_config = <<-CONFIG.strip_heredoc
           <source>
             @type http
             port 8899