diff --git a/Tracking/TrkExtrapolation/TrkExAlgs/TrkExAlgs/PropResultRootWriterSvc.h b/Tracking/TrkExtrapolation/TrkExAlgs/TrkExAlgs/PropResultRootWriterSvc.h
index edbc78a276b0c752198a7ab0148f3a813f046828..420ca7a2f2fc413999e2e55b9185e63eb910822f 100644
--- a/Tracking/TrkExtrapolation/TrkExAlgs/TrkExAlgs/PropResultRootWriterSvc.h
+++ b/Tracking/TrkExtrapolation/TrkExAlgs/TrkExAlgs/PropResultRootWriterSvc.h
@@ -33,7 +33,7 @@ class PropResultRootWriterSvc : public AthService {
       return IID_PropResultRootWriterSvc;    
     }
     
-    virtual StatusCode queryInterface(const InterfaceID& riid, void** ppvInterface) {
+    virtual StatusCode queryInterface(const InterfaceID& riid, void** ppvInterface) override {
       ATH_MSG_DEBUG("in queryInterface()");    
       if (PropResultRootWriterSvc::interfaceID().versionMatch(riid)) {
         ATH_MSG_DEBUG("matched PropResultRootWriterSvc");
diff --git a/Tracking/TrkExtrapolation/TrkExAlgs/src/PropResultRootWriterSvc.cxx b/Tracking/TrkExtrapolation/TrkExAlgs/src/PropResultRootWriterSvc.cxx
index a9905d4a8f90cac4332ec40dbd4d8bdad4f67b3b..1a3d6ba489ef81ca011266280e1bcfc5bda93720 100644
--- a/Tracking/TrkExtrapolation/TrkExAlgs/src/PropResultRootWriterSvc.cxx
+++ b/Tracking/TrkExtrapolation/TrkExAlgs/src/PropResultRootWriterSvc.cxx
@@ -29,7 +29,7 @@ StatusCode Trk::PropResultRootWriterSvc::initialize()
   const std::string treeName = m_treeName;  
   m_tree = new TTree(treeName.data(), "MyStudies");
   
-  std::string fullNtupleName = m_ntupleDirName + m_treeName;
+  std::string fullNtupleName = static_cast<std::string>(m_ntupleDirName) + m_treeName;
   CHECK(m_thistSvc->regTree(fullNtupleName, m_tree));
 
   if(m_tree == nullptr) {