diff --git a/gtsam/navigation/PreintegrationBase.cpp b/gtsam/navigation/PreintegrationBase.cpp
index da6b03019..367a62360 100644
--- a/gtsam/navigation/PreintegrationBase.cpp
+++ b/gtsam/navigation/PreintegrationBase.cpp
@@ -64,25 +64,22 @@ void PreintegrationBase::updatePreintegratedMeasurements(
     OptionalJacobian<9, 9> F) {
 
   const Matrix3 dRij = deltaRij_.matrix(); // expensive
-  const Vector3 j_acc = dRij * correctedAcc; // acceleration in current frame
+  const Vector3 i_acc = dRij * correctedAcc; // acceleration in i frame
 
   double dt22 = 0.5 * deltaT * deltaT;
-  deltaPij_ += deltaVij_ * deltaT + dt22 * j_acc;
-  deltaVij_ += deltaT * j_acc;
+  deltaPij_ += deltaVij_ * deltaT + dt22 * i_acc;
+  deltaVij_ += deltaT * i_acc;
 
   Matrix3 R_i, F_angles_angles;
-  if (F)
-    R_i = dRij; // has to be executed before updateIntegratedRotationAndDeltaT as that updates deltaRij
   updateIntegratedRotationAndDeltaT(incrR, deltaT, F ? &F_angles_angles : 0);
 
   if (F) {
-    const Matrix3 F_vel_angles = -R_i * skewSymmetric(correctedAcc) * deltaT;
+    const Matrix3 F_vel_angles = -dRij * skewSymmetric(correctedAcc) * deltaT;
     Matrix3 F_pos_angles;
-    F_pos_angles = 0.5 * F_vel_angles * deltaT;
 
     //    pos  vel             angle
     *F << //
-        I_3x3, I_3x3 * deltaT, F_pos_angles, // pos
+        I_3x3, I_3x3 * deltaT, 0.5 * F_vel_angles * deltaT, // pos
     Z_3x3, I_3x3, F_vel_angles, // vel
     Z_3x3, Z_3x3, F_angles_angles; // angle
   }