diff --git a/Service/TrackSystemSvc/src/MarlinKalTestTrack.cc b/Service/TrackSystemSvc/src/MarlinKalTestTrack.cc
index 7979379267aa921069505248c3a65aa6ebaffd44..ffedd64edb8558338e69a028ddcdcbf8021d42e1 100644
--- a/Service/TrackSystemSvc/src/MarlinKalTestTrack.cc
+++ b/Service/TrackSystemSvc/src/MarlinKalTestTrack.cc
@@ -376,7 +376,7 @@ namespace MarlinTrk {
                         bfield_z );
     
     TMatrixD cov(5,5) ;   
-    std::array<float, 15> covLCIO = ts.covMatrix;
+    auto covLCIO = ts.covMatrix;
     
     cov( 0 , 0 ) =   covLCIO[ 0] ;                   //   d0, d0
     cov( 0 , 1 ) = - covLCIO[ 1] ;                   //   d0, phi
@@ -1599,7 +1599,7 @@ namespace MarlinTrk {
     Double_t cpa  = helix.GetKappa();
     double alpha = omega / cpa  ; // conversion factor for omega (1/R) to kappa (1/Pt) 
     
-    std::array<float, 15> covLCIO; 
+    decltype(ts.covMatrix) covLCIO; 
     covLCIO[ 0] =   covK( 0 , 0 )   ; //   d0,   d0
     
     covLCIO[ 1] = - covK( 1 , 0 )   ; //   phi0, d0
diff --git a/Utilities/KiTrack/src/Tools/Fitter.cc b/Utilities/KiTrack/src/Tools/Fitter.cc
index b7a0c156d760041719a7ddf0b095fa96a6265057..8d9d18a076b6dfb48c63364a36b984eefd2aec1f 100644
--- a/Utilities/KiTrack/src/Tools/Fitter.cc
+++ b/Utilities/KiTrack/src/Tools/Fitter.cc
@@ -166,7 +166,7 @@ void Fitter::fitVXD(){
   /**********************************************************************************************/
   /*       Create a TrackStateImpl from the helix values and use it to initalise the fit        */
   /**********************************************************************************************/
-  std::array<float,15> covMatrix;
+  decltype(edm4hep::TrackState::covMatrix) covMatrix;
   
   for (unsigned icov = 0; icov<covMatrix.size(); ++icov) {
     covMatrix[icov] = 0;