diff --git a/TileCalorimeter/TileSimEvent/TileSimEvent/TileHit.h b/TileCalorimeter/TileSimEvent/TileSimEvent/TileHit.h
index 9c1ff36d28f108bd1d7e6c3fb3281f8cad43688e..a0e606306aa7f055eee2b4464c4bf1dd9e0645a4 100755
--- a/TileCalorimeter/TileSimEvent/TileSimEvent/TileHit.h
+++ b/TileCalorimeter/TileSimEvent/TileSimEvent/TileHit.h
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 //********************************************************************
@@ -102,7 +102,7 @@ public:
     operator std::string() const;
 
     /** @brief Print contents of one vector to output stream */
-    static void print_to_stream ( const std::vector<float> val,
+    static void print_to_stream ( const std::vector<float>& val,
                                   const std::string & label, 
                                   std::ostringstream & text);
 
diff --git a/TileCalorimeter/TileSimEvent/src/TileHit.cxx b/TileCalorimeter/TileSimEvent/src/TileHit.cxx
index 6dd6c3ad8047f8f03b82faf5edfd428a932a6166..44263853ff10ce9a598de02ffb3fe717d4f92462 100755
--- a/TileCalorimeter/TileSimEvent/src/TileHit.cxx
+++ b/TileCalorimeter/TileSimEvent/src/TileHit.cxx
@@ -157,7 +157,7 @@ TileHit::operator std::string() const
     return text.str();
 }
 
-void TileHit::print_to_stream ( const std::vector<float> val,
+void TileHit::print_to_stream ( const std::vector<float>& val,
                                 const std::string & label,
                                 std::ostringstream & text)
 {