diff --git a/src/absolute_pose/modules/main.cpp b/src/absolute_pose/modules/main.cpp
index 7cff9f69..ed0c271a 100644
--- a/src/absolute_pose/modules/main.cpp
+++ b/src/absolute_pose/modules/main.cpp
@@ -770,7 +770,7 @@ opengv::absolute_pose::modules::upnp_main(
     {
       Eigen::Matrix<double,10,1> s;
       upnp_fill_s(quaternion,s);
-      Eigen::Matrix<double,1,1> valueM = s.transpose() * M * s + 2.0 * C * s;
+      Eigen::Matrix<double,1,1> valueM = s.transpose() * M * s + C * s * 2.0;
       double value = valueM[0] + gamma;
       
       std::vector<std::pair<double,Eigen::Vector4d>,Eigen::aligned_allocator< std::pair<double,Eigen::Vector4d> > >::iterator