diff --git a/Trigger/TrigT1/TrigT1CaloCalibTools/src/L1CaloLArTowerEnergy.cxx b/Trigger/TrigT1/TrigT1CaloCalibTools/src/L1CaloLArTowerEnergy.cxx
index 35251b7d2f08a17a3f1316fc286a4268bf2e4cf2..86b6e7d46b264d306cb3e0ba9469fa730352d73d 100644
--- a/Trigger/TrigT1/TrigT1CaloCalibTools/src/L1CaloLArTowerEnergy.cxx
+++ b/Trigger/TrigT1/TrigT1CaloCalibTools/src/L1CaloLArTowerEnergy.cxx
@@ -99,7 +99,7 @@ namespace LVL1{
 
     mapSum::iterator it_map;
 
-    LVL1::TriggerTower *tt;
+    const LVL1::TriggerTower *tt;
     TriggerTowerCollection::const_iterator p_itTT = triggerTowerCollection.begin();
     TriggerTowerCollection::const_iterator p_itTTEnd = triggerTowerCollection.end();