diff --git a/gtsam/navigation/NavState.cpp b/gtsam/navigation/NavState.cpp
index aa33fe858..b63f25b4d 100644
--- a/gtsam/navigation/NavState.cpp
+++ b/gtsam/navigation/NavState.cpp
@@ -249,7 +249,7 @@ Vector9 NavState::coriolis(double dt, const Vector3& omega, bool secondOrder,
 
 //------------------------------------------------------------------------------
 Vector9 NavState::predictXi(const Vector9& pim, double dt,
-    const Vector3& gravity, boost::optional<const Vector3&> omegaCoriolis,
+    const Vector3& gravity, const boost::optional<Vector3>& omegaCoriolis,
     bool use2ndOrderCoriolis, OptionalJacobian<9, 9> H1,
     OptionalJacobian<9, 9> H2) const {
   const Rot3& nRb = R_;
@@ -294,7 +294,7 @@ Vector9 NavState::predictXi(const Vector9& pim, double dt,
 }
 //------------------------------------------------------------------------------
 NavState NavState::predict(const Vector9& pim, double dt,
-    const Vector3& gravity, boost::optional<const Vector3&> omegaCoriolis,
+    const Vector3& gravity, const boost::optional<Vector3>& omegaCoriolis,
     bool use2ndOrderCoriolis, OptionalJacobian<9, 9> H1,
     OptionalJacobian<9, 9> H2) const {
 
diff --git a/gtsam/navigation/NavState.h b/gtsam/navigation/NavState.h
index f9b046fe3..ed0345ada 100644
--- a/gtsam/navigation/NavState.h
+++ b/gtsam/navigation/NavState.h
@@ -210,14 +210,14 @@ public:
   /// Combine preintegrated measurements, in the form of a tangent space vector,
   /// with gravity, velocity, and Coriolis forces into a tangent space update.
   Vector9 predictXi(const Vector9& pim, double dt, const Vector3& gravity,
-      boost::optional<const Vector3&> omegaCoriolis, bool use2ndOrderCoriolis =
+      const boost::optional<Vector3>& omegaCoriolis, bool use2ndOrderCoriolis =
           false, OptionalJacobian<9, 9> H1 = boost::none,
       OptionalJacobian<9, 9> H2 = boost::none) const;
 
   /// Combine preintegrated measurements, in the form of a tangent space vector,
   /// with gravity, velocity, and Coriolis forces into a new state.
   NavState predict(const Vector9& pim, double dt, const Vector3& gravity,
-      boost::optional<const Vector3&> omegaCoriolis, bool use2ndOrderCoriolis =
+      const boost::optional<Vector3>& omegaCoriolis, bool use2ndOrderCoriolis =
           false, OptionalJacobian<9, 9> H1 = boost::none,
       OptionalJacobian<9, 9> H2 = boost::none) const;
   /// @}