diff --git a/gtsam/slam/SmartProjectionFactorP.h b/gtsam/slam/SmartProjectionFactorP.h
index 370df31bb..4cfe87513 100644
--- a/gtsam/slam/SmartProjectionFactorP.h
+++ b/gtsam/slam/SmartProjectionFactorP.h
@@ -61,7 +61,7 @@ class SmartProjectionFactorP : public SmartProjectionFactor<CAMERA> {
 
  protected:
   /// vector of keys (one for each observation) with potentially repeated keys
-  std::vector<Key> nonUniqueKeys_;
+  KeyVector nonUniqueKeys_;
 
   /// shared pointer to calibration object (one for each observation)
   std::vector<boost::shared_ptr<CALIBRATION> > K_all_;
@@ -134,7 +134,7 @@ class SmartProjectionFactorP : public SmartProjectionFactor<CAMERA> {
    * @param Ks vector of (fixed) intrinsic calibration objects
    * @param body_P_sensors vector of (fixed) extrinsic calibration objects
    */
-  void add(const MEASUREMENTS& measurements, const std::vector<Key>& poseKeys,
+  void add(const MEASUREMENTS& measurements, const KeyVector& poseKeys,
            const std::vector<boost::shared_ptr<CALIBRATION>>& Ks,
            const std::vector<Pose3> body_P_sensors = std::vector<Pose3>()) {
     assert(poseKeys.size() == measurements.size());
@@ -159,7 +159,7 @@ class SmartProjectionFactorP : public SmartProjectionFactor<CAMERA> {
   }
 
   /// return (for each observation) the (possibly non unique) keys involved in the measurements
-  const std::vector<Key> nonUniqueKeys() const {
+  const KeyVector nonUniqueKeys() const {
     return nonUniqueKeys_;
   }
 
diff --git a/gtsam/slam/tests/testSmartProjectionFactorP.cpp b/gtsam/slam/tests/testSmartProjectionFactorP.cpp
index 92172c520..8b6337cb4 100644
--- a/gtsam/slam/tests/testSmartProjectionFactorP.cpp
+++ b/gtsam/slam/tests/testSmartProjectionFactorP.cpp
@@ -833,7 +833,7 @@ TEST( SmartProjectionFactorP, hessianComparedToProjFactors_measurementsFromSameP
   measurements_lmk1_redundant.push_back(measurements_lmk1.at(0));  // we readd the first measurement
 
   // create inputs
-  std::vector<Key> keys;
+  KeyVector keys;
   keys.push_back(x1);
   keys.push_back(x2);
   keys.push_back(x3);
@@ -960,7 +960,7 @@ TEST( SmartProjectionFactorP, optimization_3poses_measurementsFromSamePose ) {
   projectToMultipleCameras(cam1, cam2, cam3, landmark3, measurements_lmk3);
 
   // create inputs
-  std::vector<Key> keys;
+  KeyVector keys;
   keys.push_back(x1);
   keys.push_back(x2);
   keys.push_back(x3);
@@ -974,7 +974,7 @@ TEST( SmartProjectionFactorP, optimization_3poses_measurementsFromSamePose ) {
   // make sure the redundancy in the keys does not create problems)
   Camera::MeasurementVector& measurements_lmk1_redundant = measurements_lmk1;
   measurements_lmk1_redundant.push_back(measurements_lmk1.at(0)); // we readd the first measurement
-  std::vector<Key> keys_redundant = keys;
+  KeyVector keys_redundant = keys;
   keys_redundant.push_back(keys.at(0)); // we readd the first key
   std::vector < boost::shared_ptr < Cal3_S2 >> sharedKs_redundant = sharedKs;
   sharedKs_redundant.push_back(sharedK);// we readd the first calibration
@@ -1096,7 +1096,7 @@ TEST( SmartProjectionFactorP, optimization_3poses_sphericalCamera ) {
   projectToMultipleCameras<Camera>(cam1, cam2, cam3, landmark3, measurements_lmk3);
 
   // create inputs
-  std::vector<Key> keys;
+  KeyVector keys;
   keys.push_back(x1);
   keys.push_back(x2);
   keys.push_back(x3);