diff --git a/gtsam/navigation/CombinedImuFactor.cpp b/gtsam/navigation/CombinedImuFactor.cpp
index 2dfaae2fd..64d555e2e 100644
--- a/gtsam/navigation/CombinedImuFactor.cpp
+++ b/gtsam/navigation/CombinedImuFactor.cpp
@@ -145,9 +145,9 @@ void PreintegratedCombinedMeasurements::integrateMeasurement(
 
   // BLOCK DIAGONAL TERMS
   D_R_R(&G_measCov_Gt) =
-      (theta_H_omega * (wCov / dt) * theta_H_omega.transpose()) +  //
-      (theta_H_biasOmegaInit * (bInitCov.block<3, 3>(3, 3) / dt) *
-       theta_H_biasOmegaInit.transpose());
+      (theta_H_omega * (wCov / dt) * theta_H_omega.transpose())  //
+      + (theta_H_biasOmegaInit * (bInitCov.block<3, 3>(3, 3) / dt) *
+         theta_H_biasOmegaInit.transpose());
 
   D_t_t(&G_measCov_Gt) =
       (pos_H_acc * (aCov / dt) * pos_H_acc.transpose())  //
diff --git a/gtsam/navigation/ScenarioRunner.cpp b/gtsam/navigation/ScenarioRunner.cpp
index 3a447dcab..9d3e258de 100644
--- a/gtsam/navigation/ScenarioRunner.cpp
+++ b/gtsam/navigation/ScenarioRunner.cpp
@@ -145,7 +145,8 @@ Eigen::Matrix<double, 15, 15> CombinedScenarioRunner::estimateCovariance(
     auto pim = integrate(T, estimatedBias, true);
     NavState sampled = predict(pim);
     Vector15 xi = Vector15::Zero();
-    xi << sampled.localCoordinates(prediction), estimatedBias_.vector();
+    xi << sampled.localCoordinates(prediction),
+        (estimatedBias_.vector() - estimatedBias.vector());
     samples.col(i) = xi;
     sum += xi;
   }