diff --git a/macro/ci/comparator.C b/macro/ci/comparator.C
index a0aacfda..08792b5b 100644
--- a/macro/ci/comparator.C
+++ b/macro/ci/comparator.C
@@ -91,6 +91,7 @@ void comparator(
   // - Dext will store the additional DAGs from other infiles
   PostProcessor *P0;
   HistosDAG *D;
+  std::vector<TObject*> test_vector;
   // std::vector<HistosDAG*> Dext; // additional DAGs
 
   /*