diff --git a/src/EXTRA-COMPUTE/compute_stress_cartesian.cpp b/src/EXTRA-COMPUTE/compute_stress_cartesian.cpp
index 0380acbb82..e1bc6bcd91 100644
--- a/src/EXTRA-COMPUTE/compute_stress_cartesian.cpp
+++ b/src/EXTRA-COMPUTE/compute_stress_cartesian.cpp
@@ -136,7 +136,7 @@ ComputeStressCartesian::ComputeStressCartesian(LAMMPS *lmp, int narg, char **arg
 
   // check for variable box dimension
   int box_incompatible = 0;
-  for (auto ifix : modify->get_fix_list()) {
+  for (auto &ifix : modify->get_fix_list()) {
     if (((dir1 == 0) && (ifix->box_change & Fix::BOX_CHANGE_X)) ||
         ((dir1 == 1) && (ifix->box_change & Fix::BOX_CHANGE_Y)) ||
         ((dir1 == 2) && (ifix->box_change & Fix::BOX_CHANGE_Z)))
diff --git a/src/GRANULAR/fix_damping_cundall.cpp b/src/GRANULAR/fix_damping_cundall.cpp
index f5ef24c3cc..cf17e91050 100644
--- a/src/GRANULAR/fix_damping_cundall.cpp
+++ b/src/GRANULAR/fix_damping_cundall.cpp
@@ -120,7 +120,7 @@ void FixDampingCundall::init()
   }
 
   bool fflag = false;
-  for (auto ifix : modify->get_fix_list()) {
+  for (auto &ifix : modify->get_fix_list()) {
     if (fflag && (comm->me == 0) && (ifix->setmask() & POST_FORCE))
       error->warning(FLERR, "Fix {} alters forces after fix damping/cundall", ifix->id);
     if (ifix == this) fflag = true;
diff --git a/src/INTEL/fix_nvt_sllod_intel.cpp b/src/INTEL/fix_nvt_sllod_intel.cpp
index eb04d65a83..404a3aff33 100644
--- a/src/INTEL/fix_nvt_sllod_intel.cpp
+++ b/src/INTEL/fix_nvt_sllod_intel.cpp
@@ -83,7 +83,7 @@ void FixNVTSllodIntel::init()
   auto deform = modify->get_fix_by_style("^deform");
   if (deform.size() < 1) error->all(FLERR,"Using fix nvt/sllod/intel with no fix deform defined");
 
-  for (auto ifix : deform) {
+  for (auto &ifix : deform) {
     auto f = dynamic_cast<FixDeform *>(ifix);
     if (f && (f->remapflag != Domain::V_REMAP))
       error->all(FLERR,"Using fix nvt/sllod/intel with inconsistent fix deform remap option");
diff --git a/src/KOKKOS/fix_nvt_sllod_kokkos.cpp b/src/KOKKOS/fix_nvt_sllod_kokkos.cpp
index 69ffdcd684..bd65a6965e 100644
--- a/src/KOKKOS/fix_nvt_sllod_kokkos.cpp
+++ b/src/KOKKOS/fix_nvt_sllod_kokkos.cpp
@@ -91,7 +91,7 @@ void FixNVTSllodKokkos<DeviceType>::init()
   if (deform.size() < 1)
     this->error->all(FLERR,"Using fix nvt/sllod/kk with no fix deform defined");
 
-  for (auto ifix : deform) {
+  for (auto &ifix : deform) {
     auto f = dynamic_cast<FixDeform *>(ifix);
     if (f && (f->remapflag != Domain::V_REMAP))
       this->error->all(FLERR,"Using fix ntv/sllod/kk with inconsistent fix deform remap option");
diff --git a/src/OPENMP/fix_nvt_sllod_omp.cpp b/src/OPENMP/fix_nvt_sllod_omp.cpp
index 5e880da7a3..700b264b9f 100644
--- a/src/OPENMP/fix_nvt_sllod_omp.cpp
+++ b/src/OPENMP/fix_nvt_sllod_omp.cpp
@@ -90,7 +90,7 @@ void FixNVTSllodOMP::init()
   auto deform = modify->get_fix_by_style("^deform");
   if (deform.size() < 1) error->all(FLERR,"Using fix nvt/sllod/omp with no fix deform defined");
 
-  for (auto ifix : deform) {
+  for (auto &ifix : deform) {
     auto f = dynamic_cast<FixDeform *>(ifix);
     if (f && (f->remapflag != Domain::V_REMAP))
       error->all(FLERR,"Using fix nvt/sllod/omp with inconsistent fix deform remap option");
diff --git a/src/REPLICA/fix_alchemy.cpp b/src/REPLICA/fix_alchemy.cpp
index 4b29da5250..2fe4417161 100644
--- a/src/REPLICA/fix_alchemy.cpp
+++ b/src/REPLICA/fix_alchemy.cpp
@@ -196,7 +196,7 @@ void FixAlchemy::init()
   synchronize_box(domain, samerank);
 
   sync_box = 0;
-  for (auto ifix : modify->get_fix_list())
+  for (const auto &ifix : modify->get_fix_list())
     if (ifix->box_change) sync_box = 1;
 }
 
diff --git a/src/fix_deform.cpp b/src/fix_deform.cpp
index 1243fef79a..02aaae5940 100644
--- a/src/fix_deform.cpp
+++ b/src/fix_deform.cpp
@@ -609,7 +609,7 @@ void FixDeform::init()
 
   rfix.clear();
 
-  for (auto ifix : modify->get_fix_list())
+  for (auto &ifix : modify->get_fix_list())
     if (ifix->rigid_flag) rfix.push_back(ifix);
 }
 
diff --git a/src/fix_nvt_sllod.cpp b/src/fix_nvt_sllod.cpp
index 7e3e8788fe..306d56388b 100644
--- a/src/fix_nvt_sllod.cpp
+++ b/src/fix_nvt_sllod.cpp
@@ -85,7 +85,7 @@ void FixNVTSllod::init()
   auto deform = modify->get_fix_by_style("^deform");
   if (deform.size() < 1) error->all(FLERR,"Using fix {} with no fix deform defined", style);
 
-  for (auto ifix : deform) {
+  for (auto &ifix : deform) {
     auto f = dynamic_cast<FixDeform *>(ifix);
     if (f && (f->remapflag != Domain::V_REMAP))
       error->all(FLERR,"Using fix {} with inconsistent fix deform remap option", style);