diff --git a/InnerDetector/InDetValidation/InDetPhysValMonitoring/src/TrackSelectionTool.h b/InnerDetector/InDetValidation/InDetPhysValMonitoring/src/TrackSelectionTool.h
index d095fc69e6ef2d3f6b3a16015c651a4f2c96f8b8..ef700268a34c737211f8107ebaee1c814f919e0c 100644
--- a/InnerDetector/InDetValidation/InDetPhysValMonitoring/src/TrackSelectionTool.h
+++ b/InnerDetector/InDetValidation/InDetPhysValMonitoring/src/TrackSelectionTool.h
@@ -10,6 +10,7 @@
 #include "xAODTracking/TrackParticle.h"
 #include "AsgTools/AsgTool.h"
 
+#include <atomic>
 
 class TrackSelectionTool:
   public virtual ::IAsgSelectionTool,
@@ -28,8 +29,8 @@ public:
 private:
   asg::AcceptInfo m_accept;
   std::vector<std::pair<std::string, std::string> > m_cuts;
-  mutable ULong64_t m_numProcessed; // !< a counter of the number of tracks proccessed
-  mutable ULong64_t m_numPassed; // !< a counter of the number of tracks that passed all cuts
+  mutable std::atomic<ULong64_t> m_numProcessed; // !< a counter of the number of tracks proccessed
+  mutable std::atomic<ULong64_t> m_numPassed; // !< a counter of the number of tracks that passed all cuts
   mutable std::vector<ULong64_t> m_numPassedCuts; // !< tracks the number of tracks that passed each cut family
 
   // Cut vales;