diff --git a/InnerDetector/InDetRecAlgs/SiSPSeededTrackFinder/src/SiSPSeededTrackFinder.cxx b/InnerDetector/InDetRecAlgs/SiSPSeededTrackFinder/src/SiSPSeededTrackFinder.cxx
index 5aa4a2a13ccb2e0e08ae5bf78909f25495d2004f..64a0196d2fcb2ebc1821dc328ad6df7f4940b921 100644
--- a/InnerDetector/InDetRecAlgs/SiSPSeededTrackFinder/src/SiSPSeededTrackFinder.cxx
+++ b/InnerDetector/InDetRecAlgs/SiSPSeededTrackFinder/src/SiSPSeededTrackFinder.cxx
@@ -174,7 +174,7 @@ StatusCode InDet::SiSPSeededTrackFinder::oldStrategy(const EventContext& ctx) co
 
   // Save good tracks in track collection
   //
-  for (const std::pair<double, Trk::Track*> & qualityAndTrack: qualitySortedTrackCandidates) {
+  for (const std::pair<const double, Trk::Track*> & qualityAndTrack: qualitySortedTrackCandidates) {
     ++counter[kNTracks];
     if (m_trackSummaryTool.isEnabled()) {
        m_trackSummaryTool->computeAndReplaceTrackSummary(*(qualityAndTrack.second),
@@ -322,7 +322,7 @@ StatusCode InDet::SiSPSeededTrackFinder::newStrategy(const EventContext& ctx) co
   filterSharedTracks(qualitySortedTrackCandidates);
 
   /// Save good tracks in track collection
-  for (const std::pair<double, Trk::Track*> & qualityAndTrack: qualitySortedTrackCandidates) {
+  for (const std::pair<const double, Trk::Track*> & qualityAndTrack: qualitySortedTrackCandidates) {
     ++counter[kNTracks];
     if (m_trackSummaryTool.isEnabled()) {
       /// Note that for run-3 the tool here is configured to not perform a hole search,
diff --git a/TileCalorimeter/TileMonitoring/src/TileRawChannelTimeMonTool.cxx b/TileCalorimeter/TileMonitoring/src/TileRawChannelTimeMonTool.cxx
index e2c0d12cff42d1b5f805a0e2282626b756d7fedd..362be27c053b2abe19d063ad790cc4c04eefeb66 100644
--- a/TileCalorimeter/TileMonitoring/src/TileRawChannelTimeMonTool.cxx
+++ b/TileCalorimeter/TileMonitoring/src/TileRawChannelTimeMonTool.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 // ********************************************************************
@@ -141,7 +141,7 @@ StatusCode TileRawChannelTimeMonTool::bookHists()
     }
   }
 
-  for (const std::pair<int, int> roses : m_timeDifferenceBetweenROS) {
+  for (const std::pair<int, int>& roses : m_timeDifferenceBetweenROS) {
     int ros1 = roses.first;
     int ros2 = roses.second;
     
@@ -367,7 +367,7 @@ StatusCode TileRawChannelTimeMonTool::fillHists()
         }
 
         int rosesPairIndex(0);
-        for (const std::pair<int, int> roses : m_timeDifferenceBetweenROS) {
+        for (const std::pair<int, int>& roses : m_timeDifferenceBetweenROS) {
           int ros1 = roses.first;
           int ros2 = roses.second;
           
@@ -377,7 +377,7 @@ StatusCode TileRawChannelTimeMonTool::fillHists()
       
       } else {
         int rosesPairIndex(0);
-        for (const std::pair<int, int> roses : m_timeDifferenceBetweenROS) {
+        for (const std::pair<int, int>& roses : m_timeDifferenceBetweenROS) {
           int ros1 = roses.first;
           int ros2 = roses.second;
           
diff --git a/Trigger/TrigT1/L1Topo/L1TopoMonitoring/src/L1TopoTestAlg.cxx b/Trigger/TrigT1/L1Topo/L1TopoMonitoring/src/L1TopoTestAlg.cxx
index 8686f7638f6841da3d7b425478fff5f807d07c4d..2dd5640a7440678187d35e71e5d9b74eb98df7a2 100644
--- a/Trigger/TrigT1/L1Topo/L1TopoMonitoring/src/L1TopoTestAlg.cxx
+++ b/Trigger/TrigT1/L1Topo/L1TopoMonitoring/src/L1TopoTestAlg.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #include "L1TopoTestAlg.h"
@@ -98,7 +98,7 @@ StatusCode L1TopoTestAlg::execute()
   }
   const std::vector<TXC::TriggerLine> & topoTriggers = topoMenu->getL1TopoConfigOutputList().getTriggerLines();
   ATH_MSG_DEBUG( "Number of trigger lines configured " << topoTriggers.size() );
-  for(const TXC::TriggerLine tl : topoTriggers) {
+  for(const TXC::TriggerLine& tl : topoTriggers) {
     ATH_MSG_VERBOSE( tl.name() << " " << tl.counter() );
   }
 
diff --git a/Trigger/TrigValidation/TrigValAlgs/src/TrigDecisionChecker.cxx b/Trigger/TrigValidation/TrigValAlgs/src/TrigDecisionChecker.cxx
index 548f36d1ff76a5c50f5e013b00c3d29f7a97369b..f5328ea8c9bac452339e0f73366fac075c122984 100755
--- a/Trigger/TrigValidation/TrigValAlgs/src/TrigDecisionChecker.cxx
+++ b/Trigger/TrigValidation/TrigValAlgs/src/TrigDecisionChecker.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 /** R.Goncalo - 21/10/2007 - add tests for TrigDecisionTool:
@@ -660,7 +660,7 @@ StatusCode TrigDecisionChecker::checkEDM(std::string trigItem){
     const auto vec = fc.get<T>();
     const auto vecbits = fc.get<xAOD::TrigPassBits>();
     std::string label="";
-    for(const auto feat:vecbits){
+    for(const auto& feat:vecbits){
         const auto *xbits=feat.cptr();
         TrigConf::HLTTriggerElement::getLabel(feat.te()->getId(), label );
         const auto *cont=(m_trigDec->ancestor<T>(feat.te())).cptr();
diff --git a/Trigger/TrigValidation/TrigValAlgs/src/TrigEDMAuxChecker.cxx b/Trigger/TrigValidation/TrigValAlgs/src/TrigEDMAuxChecker.cxx
index f3dc738cf126882e48a1db74bc635ecd8d516132..4bb3a9d7b9609c8a2a4597ed87ac97dd1707fc07 100644
--- a/Trigger/TrigValidation/TrigValAlgs/src/TrigEDMAuxChecker.cxx
+++ b/Trigger/TrigValidation/TrigValAlgs/src/TrigEDMAuxChecker.cxx
@@ -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
 */
 
 /** Adapted from code by A.Hamilton to check trigger EDM; R.Goncalo 21/11/07 */
@@ -32,16 +32,16 @@ StatusCode TrigEDMAuxChecker::initialize() {
 StatusCode TrigEDMAuxChecker::finalize() { 
 
     std::vector<std::string> auxvar;
-    for(const auto key:m_auxList){
+    for(const auto& key:m_auxList){
         ATH_MSG_INFO("REGTEST : Aux vars for " << key << " ============================");
         auxvar=m_auxmap[key];
-        for(const auto var:auxvar){
+        for(const auto& var:auxvar){
             ATH_MSG_INFO("REGTEST : " << key << " " << var);
         }
         ATH_MSG_INFO(" ========================================================");
         ATH_MSG_INFO("REGTEST : Dynamic Aux vars for " << key);
         auxvar=m_dynauxmap[key];
-        for(const auto var:auxvar){
+        for(const auto& var:auxvar){
             ATH_MSG_INFO("REGTEST : " << key << " " << var);
         }
         ATH_MSG_INFO(" ========================================================");
@@ -94,7 +94,7 @@ void TrigEDMAuxChecker::dumpDecorators(const xAOD::AuxContainerBase *x,const std
 StatusCode TrigEDMAuxChecker::execute() {
   const xAOD::AuxContainerBase* aux=0;
   StatusCode sc = StatusCode::SUCCESS;
-  for(const auto key:m_auxList){
+  for(const auto& key:m_auxList){
       sc = evtStore()->retrieve(aux,key);
       if (sc.isFailure()) {
           ATH_MSG_WARNING("REGTEST Cannot retrieve " << key);
diff --git a/Trigger/TrigValidation/TrigValAlgs/src/TrigEDMChecker.cxx b/Trigger/TrigValidation/TrigValAlgs/src/TrigEDMChecker.cxx
index 95724cf6cda32f9063dfbfcb4a6a19a0bf1a1289..86f970c7d102214ada1e001eb03c08b396e895e9 100644
--- a/Trigger/TrigValidation/TrigValAlgs/src/TrigEDMChecker.cxx
+++ b/Trigger/TrigValidation/TrigValAlgs/src/TrigEDMChecker.cxx
@@ -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
 */
 
 /** Adapted from code by A.Hamilton to check trigger EDM; R.Goncalo 21/11/07 */
@@ -4202,7 +4202,7 @@ StatusCode TrigEDMChecker::TrigCompositeNavigationToDot(std::string& returnValue
 
   // First retrieve them all (this should not be needed in future)
   const DecisionContainer* container = nullptr;
-  for (const std::string key : keys) ATH_CHECK( evtStore()->retrieve( container, key ) );
+  for (const std::string& key : keys) ATH_CHECK( evtStore()->retrieve( container, key ) );
 
   std::stringstream ss;
   ss << "digraph {" << std::endl;