diff --git a/include/util.h b/include/util.h
index 3460bbc237d9ecf640311c01659799fbf3a4dc53..92316a018be019f69287b779ab402302bcabf871 100644
--- a/include/util.h
+++ b/include/util.h
@@ -88,7 +88,7 @@ namespace util {
       const double py = 0.;
       const double pz = 0.;
       const double mass = 0.;*/
-      return ROOT::Math::PxPyPzMVector{part.p.x, part.p.y, part.p.z, part.mass()};
+      return ROOT::Math::PxPyPzMVector{part.p().x(), part.p().y(), part.p().z(), part.mass()};
     });
     return momenta;
   }