diff --git a/gtsam/slam/ProjectionFactor.h b/gtsam/slam/ProjectionFactor.h
index 67100a0ac..ada304f27 100644
--- a/gtsam/slam/ProjectionFactor.h
+++ b/gtsam/slam/ProjectionFactor.h
@@ -164,10 +164,15 @@ namespace gtsam {
     }
 
     /** return the calibration object */
-    inline const boost::shared_ptr<CALIBRATION> calibration() const {
+    const boost::shared_ptr<CALIBRATION> calibration() const {
       return K_;
     }
 
+    /** return the (optional) sensor pose with respect to the vehicle frame */
+    const boost::optional<POSE>& body_P_sensor() const {
+      return body_P_sensor_;
+    }
+
     /** return verbosity */
     inline bool verboseCheirality() const { return verboseCheirality_; }