diff --git a/gtsam_unstable/slam/tests/testSmartProjectionFactor.cpp b/gtsam_unstable/slam/tests/testSmartProjectionFactor.cpp
index 15c682505..e64d08e7d 100644
--- a/gtsam_unstable/slam/tests/testSmartProjectionFactor.cpp
+++ b/gtsam_unstable/slam/tests/testSmartProjectionFactor.cpp
@@ -375,8 +375,9 @@ TEST( SmartProjectionFactor, Hessian ){
   hessianFactor->print("Hessian factor \n");
 
   // compute triangulation from linearization point
-  // compute reprojection errors
+  // compute reprojection errors (sum squared)
   // compare with hessianFactor.info(): the bottom right element is the squared sum of the reprojection errors (normalized by the covariance)
+  // check that it is correctly scaled when using noiseProjection = [1/4  0; 0 1/4]