diff --git a/Core/include/Acts/TrackFinding/CombinatorialKalmanFilter.hpp b/Core/include/Acts/TrackFinding/CombinatorialKalmanFilter.hpp
index 30e266bf8b3..49a208547d0 100644
--- a/Core/include/Acts/TrackFinding/CombinatorialKalmanFilter.hpp
+++ b/Core/include/Acts/TrackFinding/CombinatorialKalmanFilter.hpp
@@ -575,7 +575,7 @@ class CombinatorialKalmanFilter {
                   }
                   result.lastError = res.error();
                 } else {
-                  auto fittedState = *res;
+                  const auto& fittedState = *res;
                   // Assign the fitted parameters
                   result.fittedParameters.emplace(
                       result.lastMeasurementIndices.at(result.iSmoothed),