diff --git a/src/core/ParticlePropertyIterator.hpp b/src/core/ParticlePropertyIterator.hpp
index 6b2390a62c..b10e2cae1d 100644
--- a/src/core/ParticlePropertyIterator.hpp
+++ b/src/core/ParticlePropertyIterator.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2010-2022 The ESPResSo project
+ * Copyright (C) 2023 The ESPResSo project
  *
  * This file is part of ESPResSo.
  *
@@ -16,21 +16,21 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#ifndef ESPRESSO_SRC_CORE_PARTICLE_EXTRACT_PROPERTIES_HPP
-#define ESPRESSO_SRC_CORE_PARTICLE_EXTRACT_PROPERTIES_HPP
+#pragma once
 
 #include "BoxGeometry.hpp"
 #include "Particle.hpp"
 #include "ParticleRange.hpp"
 #include "grid.hpp"
+
 #include <boost/iterator/transform_iterator.hpp>
 #include <boost/range/iterator_range.hpp>
-#include <tuple>
+
 #include <utils/Vector.hpp>
 
 namespace ParticlePropertyRange {
 
-namespace {
+namespace detail {
 template <class Kernel>
 auto create_transform_range(ParticleRange const &particles, Kernel kernel) {
   auto transform_iterator_begin =
@@ -40,32 +40,25 @@ auto create_transform_range(ParticleRange const &particles, Kernel kernel) {
   return boost::make_iterator_range<decltype(transform_iterator_begin)>(
       transform_iterator_begin, transform_iterator_end);
 }
-} // namespace
-
-auto pos_range(ParticleRange const &particles) {
-  auto return_pos = [](Particle &p) { return p.pos(); };
-  return create_transform_range(particles, return_pos);
-}
+} // namespace detail
 
 auto unfolded_pos_range(ParticleRange const &particles,
                         BoxGeometry const &box) {
   auto return_unfolded_pos = [&box](Particle &p) {
     return unfolded_position(p.pos(), p.image_box(), box.length());
   };
-  return create_transform_range(particles, return_unfolded_pos);
+  return detail::create_transform_range(particles, return_unfolded_pos);
 }
 
 auto charge_range(ParticleRange const &particles) {
-  auto return_charge = [](Particle &p) { return p.q(); };
-  return create_transform_range(particles, return_charge);
+  auto return_charge = [](Particle &p) -> double & { return p.q(); };
+  return detail::create_transform_range(particles, return_charge);
 }
 auto force_range(ParticleRange const &particles) {
   auto return_force = [](Particle &p) -> Utils::Vector3d & {
     return p.force();
   };
-  return create_transform_range(particles, return_force);
+  return detail::create_transform_range(particles, return_force);
 }
 
 } // namespace ParticlePropertyRange
-
-#endif
diff --git a/src/core/electrostatics/p3m.cpp b/src/core/electrostatics/p3m.cpp
index 220384958f..512b8612b3 100644
--- a/src/core/electrostatics/p3m.cpp
+++ b/src/core/electrostatics/p3m.cpp
@@ -399,7 +399,7 @@ static auto calc_dipole_moment(boost::mpi::communicator const &comm,
       boost::accumulate(p_q_unfolded_pos_range, Utils::Vector3d{},
                         [](Utils::Vector3d dip, auto const &q_pos) {
                           auto const p_q = boost::get<0>(q_pos);
-                          auto const p_unfolded_pos = boost::get<1>(q_pos);
+                          auto const &p_unfolded_pos = boost::get<1>(q_pos);
                           return dip + dipole_moment(p_q, p_unfolded_pos);
                         });
   return boost::mpi::all_reduce(comm, local_dip, std::plus<>());