diff --git a/src/particles/CovarianceMatrix.H b/src/particles/CovarianceMatrix.H
index 60bd15df4..23af3e5aa 100644
--- a/src/particles/CovarianceMatrix.H
+++ b/src/particles/CovarianceMatrix.H
@@ -10,14 +10,14 @@
 #ifndef IMPACTX_DISTRIBUTION_COVARIANCE_MATRIX_H
 #define IMPACTX_DISTRIBUTION_COVARIANCE_MATRIX_H
 
-#include <AMReX_Array.H>
 #include <AMReX_REAL.H>
+#include <AMReX_SmallMatrix.H>
 
 
 namespace impactx
 {
     /** this is a 6x6 matrix */
-    using CovarianceMatrix = amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6>;
+    using CovarianceMatrix = amrex::SmallMatrix<amrex::ParticleReal, 6, 6, amrex::Order::F, 1>;
 
 } // namespace impactx::distribution
 
diff --git a/src/particles/elements/Drift.H b/src/particles/elements/Drift.H
index 8bf328840..944177558 100644
--- a/src/particles/elements/Drift.H
+++ b/src/particles/elements/Drift.H
@@ -20,6 +20,7 @@
 
 #include <AMReX_Extension.H>
 #include <AMReX_REAL.H>
+#include <AMReX_SmallMatrix.H>
 
 #include <cmath>
 
@@ -168,7 +169,7 @@ namespace impactx
          */
         AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
 
-        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6>
+        amrex::SmallMatrix<amrex::ParticleReal, 6, 6, amrex::Order::F, 1>
         transport_map(RefPart & AMREX_RESTRICT refpart) {
 
             using namespace amrex::literals; // for _rt and _prt
diff --git a/src/particles/elements/mixin/lineartransport.H b/src/particles/elements/mixin/lineartransport.H
index 43641f21b..46416ba90 100644
--- a/src/particles/elements/mixin/lineartransport.H
+++ b/src/particles/elements/mixin/lineartransport.H
@@ -17,6 +17,7 @@
 #include <AMReX_Math.H>
 #include <AMReX_Extension.H>
 #include <AMReX_REAL.H>
+#include <AMReX_SmallMatrix.H>
 
 
 namespace impactx::elements
@@ -41,7 +42,7 @@ namespace impactx::elements
         ~LinearTransport () = default;
 
         // 6x6 linear transport map
-        using Map6x6 = amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6>;
+        using Map6x6 = amrex::SmallMatrix<amrex::ParticleReal, 6, 6, amrex::Order::F, 1>;
         Map6x6 m_transport_map; ///< linearized map
     };