diff --git a/Core/include/Acts/Fitter/GainMatrixUpdater.hpp b/Core/include/Acts/Fitter/GainMatrixUpdater.hpp
index 2250f42a0d89b53a254c243af75a29fdd10b9954..d25ef394e7077c1fbaea608e6ce41a625c7a6321 100644
--- a/Core/include/Acts/Fitter/GainMatrixUpdater.hpp
+++ b/Core/include/Acts/Fitter/GainMatrixUpdater.hpp
@@ -117,7 +117,8 @@ class GainMatrixUpdater {
           trackState.chi2() =
               (residual.transpose() *
                ((cov_t::Identity() - H * K) * calibrated_covariance).inverse() *
-               residual);
+               residual)
+                  .eval()(0, 0);
         });
 
     return Result<void>::success();