1 files changed, 4 insertions, 5 deletions
diff --git a/Source/Diagnostics/ReducedDiags/ParticleHistogram.cpp b/Source/Diagnostics/ReducedDiags/ParticleHistogram.cpp
index 0a93da8d1..85624c6a1 100644
--- a/Source/Diagnostics/ReducedDiags/ParticleHistogram.cpp
+++ b/Source/Diagnostics/ReducedDiags/ParticleHistogram.cpp
@@ -65,7 +65,7 @@ ParticleHistogram::ParticleHistogram (std::string rd_name)
     }
 
     // get MultiParticleContainer class object
-    auto & mypc = WarpX::GetInstance().GetPartContainer();
+    const auto & mypc = WarpX::GetInstance().GetPartContainer();
     // get species names (std::vector<std::string>)
     auto const species_names = mypc.GetSpeciesNames();
     // select species
@@ -88,9 +88,8 @@ ParticleHistogram::ParticleHistogram (std::string rd_name)
         if ( m_IsNotRestart )
         {
             // open file
-            std::ofstream ofs;
-            ofs.open(m_path + m_rd_name + "." + m_extension,
-                std::ofstream::out | std::ofstream::app);
+            std::ofstream ofs{m_path + m_rd_name + "." + m_extension,
+                std::ofstream::out | std::ofstream::app};
             // write header row
             ofs << "#";
             ofs << "[1]step()";
@@ -127,7 +126,7 @@ void ParticleHistogram::ComputeDiags (int step)
     auto const t = warpx.gett_new(0);
 
     // get MultiParticleContainer class object
-    auto & mypc = warpx.GetPartContainer();
+    const auto & mypc = warpx.GetPartContainer();
 
     // get WarpXParticleContainer class object
     auto const & myspc = mypc.GetParticleContainer(m_selected_species_id);