diff --git a/gtsam.h b/gtsam.h
index 823a2606d..9aa19db10 100644
--- a/gtsam.h
+++ b/gtsam.h
@@ -2347,8 +2347,7 @@ class CombinedImuFactorPreintegratedMeasurements {
 
 virtual class CombinedImuFactor : gtsam::NonlinearFactor {
   CombinedImuFactor(size_t pose_i, size_t vel_i, size_t pose_j, size_t vel_j, size_t bias_i, size_t bias_j,
-      const gtsam::CombinedImuFactorPreintegratedMeasurements& CombinedPreintegratedMeasurements, Vector gravity, Vector omegaCoriolis,
-      const gtsam::noiseModel::Base* model);
+      const gtsam::CombinedImuFactorPreintegratedMeasurements& CombinedPreintegratedMeasurements, Vector gravity, Vector omegaCoriolis);
 
   // Standard Interface
   gtsam::CombinedImuFactorPreintegratedMeasurements preintegratedMeasurements() const;
diff --git a/gtsam/navigation/CombinedImuFactor.h b/gtsam/navigation/CombinedImuFactor.h
index bd0b9c03b..7d0e78a6f 100644
--- a/gtsam/navigation/CombinedImuFactor.h
+++ b/gtsam/navigation/CombinedImuFactor.h
@@ -341,8 +341,8 @@ namespace gtsam {
     /** Constructor */
     CombinedImuFactor(Key pose_i, Key vel_i, Key pose_j, Key vel_j, Key bias_i, Key bias_j,
         const CombinedPreintegratedMeasurements& preintegratedMeasurements, const Vector3& gravity, const Vector3& omegaCoriolis,
-        const SharedNoiseModel& model, boost::optional<const Pose3&> body_P_sensor = boost::none, const bool use2ndOrderCoriolis = false) :
-      Base(model, pose_i, vel_i, pose_j, vel_j, bias_i, bias_j),
+        boost::optional<const Pose3&> body_P_sensor = boost::none, const bool use2ndOrderCoriolis = false) :
+      Base(noiseModel::Gaussian::Covariance(preintegratedMeasurements.PreintMeasCov), pose_i, vel_i, pose_j, vel_j, bias_i, bias_j),
       preintegratedMeasurements_(preintegratedMeasurements),
       gravity_(gravity),
       omegaCoriolis_(omegaCoriolis),
diff --git a/gtsam/navigation/tests/testCombinedImuFactor.cpp b/gtsam/navigation/tests/testCombinedImuFactor.cpp
index a07539d1e..1a8b6160d 100644
--- a/gtsam/navigation/tests/testCombinedImuFactor.cpp
+++ b/gtsam/navigation/tests/testCombinedImuFactor.cpp
@@ -183,7 +183,7 @@ TEST( CombinedImuFactor, ErrorWithBiases )
     ImuFactor factor(X(1), V(1), X(2), V(2), B(1), pre_int_data, gravity, omegaCoriolis);
 
     noiseModel::Gaussian::shared_ptr Combinedmodel = noiseModel::Gaussian::Covariance(Combined_pre_int_data.PreintMeasCov);
-    CombinedImuFactor Combinedfactor(X(1), V(1), X(2), V(2), B(1), B(2), Combined_pre_int_data, gravity, omegaCoriolis, Combinedmodel);
+    CombinedImuFactor Combinedfactor(X(1), V(1), X(2), V(2), B(1), B(2), Combined_pre_int_data, gravity, omegaCoriolis);
 
 
     Vector errorExpected = factor.evaluateError(x1, v1, x2, v2, bias);