diff --git a/src/AMOEBA/amoeba_file.cpp b/src/AMOEBA/amoeba_file.cpp
index 0b707047bf..99a8474a81 100644
--- a/src/AMOEBA/amoeba_file.cpp
+++ b/src/AMOEBA/amoeba_file.cpp
@@ -79,7 +79,7 @@ void PairAmoeba::read_prmfile(char *filename)
 
   int me = comm->me;
   FILE *fptr;
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
 
   if (me == 0) {
     fptr = utils::open_potential(filename, lmp, nullptr);
@@ -179,8 +179,7 @@ void PairAmoeba::read_prmfile(char *filename)
       for (int i = 1; i <= n_amtype; i++) nmultiframe[i] = 0;
     }
 
-    char next[MAXLINE];
-    next[0] = '\0';
+    char next[MAXLINE] = {'\0'};
     bool has_next = false;
     int n;
     while (true) {
@@ -381,7 +380,7 @@ void PairAmoeba::read_keyfile(char *filename)
 
   int me = comm->me;
   FILE *fptr;
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
   if (me == 0) {
     fptr = utils::open_potential(filename, lmp, nullptr);
     if (fptr == nullptr)
diff --git a/src/AMOEBA/fix_amoeba_bitorsion.cpp b/src/AMOEBA/fix_amoeba_bitorsion.cpp
index 2a3618569f..f814f4109a 100644
--- a/src/AMOEBA/fix_amoeba_bitorsion.cpp
+++ b/src/AMOEBA/fix_amoeba_bitorsion.cpp
@@ -724,7 +724,7 @@ double FixAmoebaBiTorsion::compute_scalar()
 
 void FixAmoebaBiTorsion::read_grid_data(char *bitorsion_file)
 {
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
   char *eof;
 
   FILE *fp = nullptr;
diff --git a/src/BOCS/fix_bocs.cpp b/src/BOCS/fix_bocs.cpp
index 58da1430b0..dbf053b407 100644
--- a/src/BOCS/fix_bocs.cpp
+++ b/src/BOCS/fix_bocs.cpp
@@ -616,8 +616,8 @@ int FixBocs::read_F_table( char *filename, int p_basis_type )
     // Data file lines hold two floating point numbers.
     // Line length we allocate should be long enough without being too long.
     // 128 seems safe for a line we expect to be < 30 chars.
-    const int MAX_F_TABLE_LINE_LENGTH = 128;
-    char line[MAX_F_TABLE_LINE_LENGTH];
+    constexpr int MAX_F_TABLE_LINE_LENGTH = 128;
+    char line[MAX_F_TABLE_LINE_LENGTH] = {'\0'};
     std::vector<std::string> inputLines;
     while (fgets(line, MAX_F_TABLE_LINE_LENGTH, fpi)) {
       inputLines.emplace_back(line);
diff --git a/src/DPD-REACT/fix_eos_table.cpp b/src/DPD-REACT/fix_eos_table.cpp
index 9e17ab450e..42567119df 100644
--- a/src/DPD-REACT/fix_eos_table.cpp
+++ b/src/DPD-REACT/fix_eos_table.cpp
@@ -194,7 +194,7 @@ void FixEOStable::free_table(Table *tb)
 
 void FixEOStable::read_table(Table *tb, Table *tb2, char *file, char *keyword)
 {
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
 
   // open file
 
diff --git a/src/DPD-REACT/fix_eos_table_rx.cpp b/src/DPD-REACT/fix_eos_table_rx.cpp
index 24f57e399f..bf71b502f0 100644
--- a/src/DPD-REACT/fix_eos_table_rx.cpp
+++ b/src/DPD-REACT/fix_eos_table_rx.cpp
@@ -318,7 +318,8 @@ void FixEOStableRX::read_file(char *file)
 
   // one set of params can span multiple lines
   int n,nwords,ispecies;
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
 
   while (true) {
@@ -414,7 +415,7 @@ void FixEOStableRX::free_table(Table *tb)
 
 void FixEOStableRX::read_table(Table *tb, Table *tb2, char *file, char *keyword)
 {
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
 
   // open file
 
diff --git a/src/DPD-REACT/fix_rx.cpp b/src/DPD-REACT/fix_rx.cpp
index 43ff5bfe0e..96f8ec6a7d 100644
--- a/src/DPD-REACT/fix_rx.cpp
+++ b/src/DPD-REACT/fix_rx.cpp
@@ -250,7 +250,8 @@ void FixRX::post_constructor()
   // Assign species names to tmpspecies array and determine the number of unique species
 
   int n;
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   char * word;
 
@@ -784,7 +785,8 @@ void FixRX::read_file(char *file)
   // Count the number of reactions from kinetics file
 
   int n,ispecies;
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
 
   while (true) {
diff --git a/src/DPD-REACT/pair_exp6_rx.cpp b/src/DPD-REACT/pair_exp6_rx.cpp
index d2294442ac..e0ac9c0b27 100644
--- a/src/DPD-REACT/pair_exp6_rx.cpp
+++ b/src/DPD-REACT/pair_exp6_rx.cpp
@@ -728,7 +728,8 @@ void PairExp6rx::read_file(char *file)
   // one set of params can span multiple lines
 
   int n,nwords,ispecies;
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
 
   while (true) {
@@ -835,7 +836,8 @@ void PairExp6rx::read_file2(char *file)
 
   // one set of params can span multiple lines
   int n,nwords;
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
 
   while (true) {
diff --git a/src/DPD-REACT/pair_multi_lucy.cpp b/src/DPD-REACT/pair_multi_lucy.cpp
index 9810039c8f..a51e7b551e 100644
--- a/src/DPD-REACT/pair_multi_lucy.cpp
+++ b/src/DPD-REACT/pair_multi_lucy.cpp
@@ -344,7 +344,7 @@ double PairMultiLucy::init_one(int i, int j)
 
 void PairMultiLucy::read_table(Table *tb, char *file, char *keyword)
 {
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
 
   // open file
 
diff --git a/src/DPD-REACT/pair_multi_lucy_rx.cpp b/src/DPD-REACT/pair_multi_lucy_rx.cpp
index e0ce3f62fb..4b61bf3a4d 100644
--- a/src/DPD-REACT/pair_multi_lucy_rx.cpp
+++ b/src/DPD-REACT/pair_multi_lucy_rx.cpp
@@ -483,7 +483,7 @@ double PairMultiLucyRX::init_one(int i, int j)
 
 void PairMultiLucyRX::read_table(Table *tb, char *file, char *keyword)
 {
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
 
   // open file
 
diff --git a/src/INTEL/pair_snap_intel.cpp b/src/INTEL/pair_snap_intel.cpp
index 7cf5e00dcc..c9a4ed3d5a 100644
--- a/src/INTEL/pair_snap_intel.cpp
+++ b/src/INTEL/pair_snap_intel.cpp
@@ -445,7 +445,8 @@ void PairSNAPIntel::read_files(char *coefffilename, char *paramfilename)
                                    coefffilename, utils::getsyserror());
   }
 
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   int nwords = 0;
   while (nwords == 0) {
diff --git a/src/KIM/kim_interactions.cpp b/src/KIM/kim_interactions.cpp
index a8887ab275..c0ec0ee28e 100644
--- a/src/KIM/kim_interactions.cpp
+++ b/src/KIM/kim_interactions.cpp
@@ -281,7 +281,8 @@ void KimInteractions::KIM_SET_TYPE_PARAMETERS(const std::string &input_line) con
     if (fp == nullptr) error->one(FLERR, "Parameter file {} not found", filename);
   }
 
-  char line[MAXLINE], *ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int n, eof = 0;
 
   while (true) {
diff --git a/src/KOKKOS/pair_exp6_rx_kokkos.cpp b/src/KOKKOS/pair_exp6_rx_kokkos.cpp
index 3d3d9bf27f..dad7413669 100644
--- a/src/KOKKOS/pair_exp6_rx_kokkos.cpp
+++ b/src/KOKKOS/pair_exp6_rx_kokkos.cpp
@@ -1702,7 +1702,8 @@ void PairExp6rxKokkos<DeviceType>::read_file(char *file)
   // one set of params can span multiple lines
 
   int n,nwords,ispecies;
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
 
   while (true) {
diff --git a/src/ML-IAP/mliap_descriptor_snap.cpp b/src/ML-IAP/mliap_descriptor_snap.cpp
index 1380c5c1ea..892dc8a004 100644
--- a/src/ML-IAP/mliap_descriptor_snap.cpp
+++ b/src/ML-IAP/mliap_descriptor_snap.cpp
@@ -380,7 +380,8 @@ void MLIAPDescriptorSNAP::read_paramfile(char *paramfilename)
                  utils::getsyserror());
   }
 
-  char line[MAXLINE], *ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   int n;
 
diff --git a/src/ML-IAP/mliap_descriptor_so3.cpp b/src/ML-IAP/mliap_descriptor_so3.cpp
index 59b54cfee7..2308961913 100644
--- a/src/ML-IAP/mliap_descriptor_so3.cpp
+++ b/src/ML-IAP/mliap_descriptor_so3.cpp
@@ -90,7 +90,8 @@ void MLIAPDescriptorSO3::read_paramfile(char *paramfilename)
                  utils::getsyserror());
   }
 
-  char line[MAXLINE], *ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   int n, nwords;
 
diff --git a/src/ML-IAP/mliap_model.cpp b/src/ML-IAP/mliap_model.cpp
index b23f02d343..c6df037c04 100644
--- a/src/ML-IAP/mliap_model.cpp
+++ b/src/ML-IAP/mliap_model.cpp
@@ -93,7 +93,8 @@ void MLIAPModelSimple::read_coeffs(char *coefffilename)
                  utils::getsyserror());
   }
 
-  char line[MAXLINE], *ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
 
   int n;
diff --git a/src/ML-IAP/mliap_model_nn.cpp b/src/ML-IAP/mliap_model_nn.cpp
index 685b0ce779..6695109f91 100644
--- a/src/ML-IAP/mliap_model_nn.cpp
+++ b/src/ML-IAP/mliap_model_nn.cpp
@@ -75,7 +75,8 @@ void MLIAPModelNN::read_coeffs(char *coefffilename)
                  utils::getsyserror());
   }
 
-  char line[MAXLINE], *ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int n, eof = 0, nwords = 0;
   while (nwords == 0) {
     if (comm->me == 0) {
diff --git a/src/ML-POD/fitpod_command.cpp b/src/ML-POD/fitpod_command.cpp
index 9ffb057173..ef39962e0b 100644
--- a/src/ML-POD/fitpod_command.cpp
+++ b/src/ML-POD/fitpod_command.cpp
@@ -150,7 +150,8 @@ int FitPOD::read_data_file(double *fitting_weights, std::string &file_format,
 
   // loop through lines of training data file and parse keywords
 
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   while (true) {
     if (comm->me == 0) {
@@ -251,7 +252,8 @@ int FitPOD::get_number_atom_exyz(std::vector<int>& num_atom, int& num_atom_sum,
       error->one(FLERR,"Cannot open POD coefficient file {}: ", filename, utils::getsyserror());
   }
 
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   int num_configs = 0;
   num_atom_sum = 0;
@@ -323,7 +325,8 @@ void FitPOD::read_exyz_file(double *lattice, double *stress, double *energy, dou
       error->one(FLERR,"Cannot open POD coefficient file {}: ", filename, utils::getsyserror());
   }
 
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   int cfi = 0;
   int nat = 0;
diff --git a/src/ML-POD/mlpod.cpp b/src/ML-POD/mlpod.cpp
index fba780bfae..088b9abadc 100644
--- a/src/ML-POD/mlpod.cpp
+++ b/src/ML-POD/mlpod.cpp
@@ -302,7 +302,8 @@ void MLPOD::read_pod(const std::string &pod_file)
 
   // loop through lines of POD file and parse keywords
 
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   while (true) {
     if (comm->me == 0) {
@@ -639,7 +640,8 @@ void MLPOD::read_coeff_file(const std::string &coeff_file)
 
   // check format for first line of file
 
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   int nwords = 0;
   while (nwords == 0) {
diff --git a/src/ML-RANN/pair_rann.cpp b/src/ML-RANN/pair_rann.cpp
index aa3578f2c9..4ec1f45703 100644
--- a/src/ML-RANN/pair_rann.cpp
+++ b/src/ML-RANN/pair_rann.cpp
@@ -616,7 +616,8 @@ void PairRANN::read_weight(std::vector<std::string> line,std::vector<std::string
 
 void PairRANN::read_bias(std::vector<std::string> line,std::vector<std::string> line1,FILE* fp,char *filename,int *linenum) {
   int i,j,l;
-  char linetemp[MAXLINE],*ptr;
+  char linetemp[MAXLINE] = {'\0'};
+  char *ptr;
   for (l=0;l<nelements;l++) {
     if (line[1].compare(elements[l])==0) {
       if (net[l].layers==0)error->one(filename,*linenum-1,"networklayers must be defined before biases.");
diff --git a/src/ML-SNAP/pair_snap.cpp b/src/ML-SNAP/pair_snap.cpp
index 245ff4acc4..f0fcd5c4e7 100644
--- a/src/ML-SNAP/pair_snap.cpp
+++ b/src/ML-SNAP/pair_snap.cpp
@@ -475,7 +475,8 @@ void PairSNAP::read_files(char *coefffilename, char *paramfilename)
                                    coefffilename, utils::getsyserror());
   }
 
-  char line[MAXLINE],*ptr;
+  char line[MAXLINE] = {'\0'};
+  char *ptr;
   int eof = 0;
   int nwords = 0;
   while (nwords == 0) {
diff --git a/src/PHONON/fix_phonon.cpp b/src/PHONON/fix_phonon.cpp
index 7787cefd6e..9ed39bc861 100644
--- a/src/PHONON/fix_phonon.cpp
+++ b/src/PHONON/fix_phonon.cpp
@@ -555,7 +555,7 @@ void FixPhonon::readmap()
   }
 
   // read from map file for others
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
   FILE *fp = fopen(mapfile, "r");
   if (fp == nullptr)
     error->all(FLERR,"Cannot open input map file {}: {}", mapfile, utils::getsyserror());
diff --git a/src/REACTION/fix_bond_react.cpp b/src/REACTION/fix_bond_react.cpp
index e528ad30c7..34a5d3bcec 100644
--- a/src/REACTION/fix_bond_react.cpp
+++ b/src/REACTION/fix_bond_react.cpp
@@ -3922,7 +3922,8 @@ read map file
 void FixBondReact::read_map_file(int myrxn)
 {
   int rv;
-  char line[MAXLINE],keyword[MAXLINE];
+  char line[MAXLINE] = {'\0'};
+  char keyword[MAXLINE] = {'\0'};
   char *eof,*ptr;
 
   // skip 1st line of file
diff --git a/src/REPLICA/neb.cpp b/src/REPLICA/neb.cpp
index 5ab2a14137..8ee8fe303c 100644
--- a/src/REPLICA/neb.cpp
+++ b/src/REPLICA/neb.cpp
@@ -437,7 +437,7 @@ void NEB::readfile(char *file, int flag)
   int i, nchunk, eofflag, nlines;
   tagint tag;
   char *eof, *start, *next, *buf;
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
   double delx, dely, delz;
 
   if (me_universe == 0 && universe->uscreen)
diff --git a/src/RIGID/fix_rigid.cpp b/src/RIGID/fix_rigid.cpp
index bd3c53e3ec..7a63c52220 100644
--- a/src/RIGID/fix_rigid.cpp
+++ b/src/RIGID/fix_rigid.cpp
@@ -2300,7 +2300,7 @@ void FixRigid::readfile(int which, double *vec, double **array1, double **array2
   int nlines;
   FILE *fp;
   char *eof,*start,*next,*buf;
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
 
   // open file and read and parse first non-empty, non-comment line containing the number of bodies
   if (comm->me == 0) {
diff --git a/src/RIGID/fix_rigid_small.cpp b/src/RIGID/fix_rigid_small.cpp
index 5905e44595..487e3ee308 100644
--- a/src/RIGID/fix_rigid_small.cpp
+++ b/src/RIGID/fix_rigid_small.cpp
@@ -2470,7 +2470,7 @@ void FixRigidSmall::readfile(int which, double **array, int *inbody)
   int nchunk,eofflag,nlines,xbox,ybox,zbox;
   FILE *fp;
   char *eof,*start,*next,*buf;
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
 
   // create local hash with key/value pairs
   // key = mol ID of bodies my atoms own
diff --git a/src/SPIN/neb_spin.cpp b/src/SPIN/neb_spin.cpp
index de680cd1e7..ac54f069a9 100644
--- a/src/SPIN/neb_spin.cpp
+++ b/src/SPIN/neb_spin.cpp
@@ -375,7 +375,7 @@ void NEBSpin::readfile(char *file, int flag)
   int i,nchunk,eofflag,nlines;
   tagint tag;
   char *eof,*start,*next,*buf;
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
   double musp,xx,yy,zz,spx,spy,spz;
 
   if (me_universe == 0 && universe->uscreen)
diff --git a/src/angle_write.cpp b/src/angle_write.cpp
index 62e780b32e..0a0c457000 100644
--- a/src/angle_write.cpp
+++ b/src/angle_write.cpp
@@ -147,7 +147,7 @@ void AngleWrite::command(int narg, char **arg)
     writer->input->one("mass * 1.0");
     writer->input->one(fmt::format("angle_style {}", force->angle_style));
     FILE *coeffs;
-    char line[MAXLINE];
+    char line[MAXLINE] = {'\0'};
     coeffs = fopen(coeffs_file.c_str(), "r");
     for (int i = 0; i < atom->nangletypes; ++i) {
       fgets(line, MAXLINE, coeffs);
diff --git a/src/dihedral_write.cpp b/src/dihedral_write.cpp
index ace1de309d..375373523b 100644
--- a/src/dihedral_write.cpp
+++ b/src/dihedral_write.cpp
@@ -148,7 +148,7 @@ void DihedralWrite::command(int narg, char **arg)
     writer->input->one("mass * 1.0");
     writer->input->one(fmt::format("dihedral_style {}", force->dihedral_style));
     FILE *coeffs;
-    char line[MAXLINE];
+    char line[MAXLINE] = {'\0'};
     coeffs = fopen(coeffs_file.c_str(), "r");
     for (int i = 0; i < atom->ndihedraltypes; ++i) {
       fgets(line, MAXLINE, coeffs);
diff --git a/src/molecule.cpp b/src/molecule.cpp
index 59f84154db..d0c8e793b3 100644
--- a/src/molecule.cpp
+++ b/src/molecule.cpp
@@ -416,7 +416,7 @@ void Molecule::compute_inertia()
 
 void Molecule::read(int flag)
 {
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
   char *eof;
 
   // skip 1st line of file
@@ -2134,7 +2134,7 @@ void Molecule::readline(char *line)
 
 std::string Molecule::parse_keyword(int flag, char *line)
 {
-  char line2[MAXLINE];
+  char line2[MAXLINE] = {'\0'};
   if (flag) {
 
     // read upto non-blank line plus 1 following line
diff --git a/src/procmap.cpp b/src/procmap.cpp
index 37f1fa3889..71e1cf5a6b 100644
--- a/src/procmap.cpp
+++ b/src/procmap.cpp
@@ -282,7 +282,7 @@ void ProcMap::custom_grid(char *cfile, int nprocs,
   int me;
   MPI_Comm_rank(world,&me);
 
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
   FILE *fp = nullptr;
 
   if (me == 0) {
diff --git a/src/universe.cpp b/src/universe.cpp
index 69e96aaa9e..edd5b01031 100644
--- a/src/universe.cpp
+++ b/src/universe.cpp
@@ -69,7 +69,7 @@ Universe::~Universe()
 
 void Universe::reorder(char *style, char *arg)
 {
-  char line[MAXLINE];
+  char line[MAXLINE] = {'\0'};
 
   if (uworld != uorig) MPI_Comm_free(&uworld);