diff --git a/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MdtSegmentT0Fitter/MdtSegmentT0Fitter/ATLAS_CHECK_THREAD_SAFETY b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MdtSegmentT0Fitter/MdtSegmentT0Fitter/ATLAS_CHECK_THREAD_SAFETY
new file mode 100644
index 0000000000000000000000000000000000000000..59082049ca5964344deaa950939f4573bdd23829
--- /dev/null
+++ b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MdtSegmentT0Fitter/MdtSegmentT0Fitter/ATLAS_CHECK_THREAD_SAFETY
@@ -0,0 +1 @@
+MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MdtSegmentT0Fitter
diff --git a/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonLayerSegmentMakerTools/ATLAS_CHECK_THREAD_SAFETY b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonLayerSegmentMakerTools/ATLAS_CHECK_THREAD_SAFETY
new file mode 100644
index 0000000000000000000000000000000000000000..85053ce13a75120ce7959243aa277adadcf7ac8d
--- /dev/null
+++ b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonLayerSegmentMakerTools/ATLAS_CHECK_THREAD_SAFETY
@@ -0,0 +1 @@
+MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonLayerSegmentMakerTools
diff --git a/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonLayerSegmentMakerTools/src/MuonLayerSegmentFinderTool.cxx b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonLayerSegmentMakerTools/src/MuonLayerSegmentFinderTool.cxx
index f0470126f743ff7ee94091f102f288e81f1ce6c1..6547f0f1cc9e9c21727f528a841bb4182408d2ef 100644
--- a/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonLayerSegmentMakerTools/src/MuonLayerSegmentFinderTool.cxx
+++ b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonLayerSegmentMakerTools/src/MuonLayerSegmentFinderTool.cxx
@@ -214,8 +214,8 @@ MuonLayerSegmentFinderTool::findMdtSegmentsFromHough(
         findMdtSegments(intersection, mdts, clusters, segments);
 
         // clean-up memory
-        for (auto hit : mdts) delete hit;
-        for (auto hit : clusters) delete hit;
+        for (const auto *hit : mdts) delete hit;
+        for (const auto *hit : clusters) delete hit;
         ATH_MSG_DEBUG("  Done maximum: new segments " << segments.size() - nprevSegments);
     }
     ATH_MSG_DEBUG("  Done with layer: new segments " << segments.size() - nprevSegments);
@@ -304,23 +304,23 @@ MuonLayerSegmentFinderTool::findClusterSegments(const MuonSystemExtension::Inter
     const std::vector<const MuonClusterOnTrack*>& clustersMM   = layerROTs.getClusters(MuonStationIndex::MM);
 
     std::vector<const MuonClusterOnTrack*> clusters;
-    if (clustersSTGC.size() > 0) {
+    if (!clustersSTGC.empty()) {
         ATH_MSG_DEBUG(" STGC clusters " << clustersSTGC.size());
-        for (auto cl : clustersSTGC) {
+        for (const auto *cl : clustersSTGC) {
             clusters.push_back(cl);
         }
     }
-    if (clustersMM.size() > 0) {
+    if (!clustersMM.empty()) {
         ATH_MSG_DEBUG(" MM clusters " << clustersMM.size());
-        for (auto cl : clustersMM) {
+        for (const auto *cl : clustersMM) {
             clusters.push_back(cl);
         }
     }
 
     std::vector<MuonSegment*> foundSegments;
     m_clusterSegMakerNSW->find(clusters, foundSegments);
-    if (foundSegments.size() > 0) {
-        for (auto seg : foundSegments) {
+    if (!foundSegments.empty()) {
+        for (auto *seg : foundSegments) {
             ATH_MSG_DEBUG(" NSW segment " << m_printer->print(*seg));
             segments.push_back(std::shared_ptr<const MuonSegment>(seg));
             ATH_MSG_DEBUG(" total segments " << segments.size());
diff --git a/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonSegmentCleaner/MuonSegmentCleaner/ATLAS_CHECK_THREAD_SAFETY b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonSegmentCleaner/MuonSegmentCleaner/ATLAS_CHECK_THREAD_SAFETY
new file mode 100644
index 0000000000000000000000000000000000000000..7327e5c28a4f32cf158a87ae124198db5005e381
--- /dev/null
+++ b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonSegmentCleaner/MuonSegmentCleaner/ATLAS_CHECK_THREAD_SAFETY
@@ -0,0 +1 @@
+MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonSegmentCleaner
diff --git a/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonSegmentCleaner/src/MuonSegmentAmbiCleaner.cxx b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonSegmentCleaner/src/MuonSegmentAmbiCleaner.cxx
index 473bd8492fa2669bc76df627b697962304a5f273..78b150abed1898ee956b6c67839eca445c1c36f7 100644
--- a/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonSegmentCleaner/src/MuonSegmentAmbiCleaner.cxx
+++ b/MuonSpectrometer/MuonReconstruction/MuonSegmentMakers/MuonSegmentMakerTools/MuonSegmentCleaner/src/MuonSegmentAmbiCleaner.cxx
@@ -84,7 +84,7 @@ const Muon::MuonSegment* MuonSegmentAmbiCleaner::resolve(const Muon::MuonSegment
     if (rot)
       {
 	rots.push_back(rot);
-	crots.push_back(0);
+	crots.push_back(nullptr);
       }
 
     else 
@@ -263,10 +263,10 @@ const Muon::MuonSegment* MuonSegmentAmbiCleaner::resolve(const Muon::MuonSegment
 	 for(unsigned int j = 0; j < nphi ; j++ )  {
 	   if (crots_phi[j] == crots_phi[i] && j!=i)
 	     {
-	       crots_phi[j]=0;
+	       crots_phi[j]=nullptr;
 	     }
 	 }
-	 crots_phi[i]=0;
+	 crots_phi[i]=nullptr;
        }
    }
 
@@ -314,7 +314,7 @@ const Muon::MuonSegment* MuonSegmentAmbiCleaner::resolve(const Muon::MuonSegment
  
   const Trk::LocalDirection locSegmentDir(segment->localDirection());
   Amg::Vector2D locSegmentPos(lSegmentPos.x(),lSegmentPos.y());
-  const Amg::MatrixX locSegmenterr(segment->localCovariance());
+  const Amg::MatrixX& locSegmenterr(segment->localCovariance());
   Trk::FitQuality* fitQuality = segment->fitQuality()->clone();
   Muon::MuonSegment* newSegment = new Muon::MuonSegment(locSegmentPos,locSegmentDir,locSegmenterr,psf,meas_keep,fitQuality);