diff --git a/include/util.h b/include/util.h
index ef12813132ba7a588f6e0cdc5cd61955ff1a1eb9..171713d4f67c51ca8961aba0453735cac4cd1881 100644
--- a/include/util.h
+++ b/include/util.h
@@ -86,7 +86,8 @@ namespace util {
       const double px = part.p.x;
       const double py = part.p.y;
       const double pz = part.p.z;
-      return ROOT::Math::PxPyPzMVector{px, py, pz, part.mass};
+      const double mass = part.mass;
+      return ROOT::Math::PxPyPzMVector{px, py, pz, mass};
     });
     return momenta;
   }