diff --git a/test/helper.rb b/test/helper.rb
index 48bfc746..132b1f62 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -35,7 +35,8 @@ class Test::Unit::TestCase
   def site_configuration(overrides = {})
     full_overrides = build_configs(overrides, build_configs({"destination" => dest_dir}))
     build_configs({
-      "source"      => source_dir,
+      "source"       => source_dir,
+      "full_rebuild" => true
     }, full_overrides)
   end