diff --git a/Service/TrackSystemSvc/src/LCIOTrackPropagators.cc b/Service/TrackSystemSvc/src/LCIOTrackPropagators.cc
index 22fb8665f77fe8dfb162997685f86224514d2218..a5ab0265dd3d21e32dcab7c48eb543da39d6968e 100644
--- a/Service/TrackSystemSvc/src/LCIOTrackPropagators.cc
+++ b/Service/TrackSystemSvc/src/LCIOTrackPropagators.cc
@@ -100,7 +100,7 @@ namespace LCIOTrackPropagators{
     
     CLHEP::HepSymMatrix covPrime =  cov0.similarity(propagatorMatrix);
     
-    std::array<float,15> cov;
+    decltype(edm4hep::TrackState::covMatrix) cov;
     
     icov = 0 ;