diff --git a/src/atom_vec.cpp b/src/atom_vec.cpp
index ef276bcf6a..491212ad5c 100644
--- a/src/atom_vec.cpp
+++ b/src/atom_vec.cpp
@@ -24,6 +24,7 @@
 #include "memory.h"
 #include "error.h"
 #include "utils.h"
+#include "tokenizer.h"
 
 using namespace LAMMPS_NS;
 using namespace MathConst;
@@ -2457,11 +2458,10 @@ int AtomVec::process_fields(char *str, const char *default_str, Method *method)
   }
 
   // tokenize words in both strings
+  Tokenizer words(str, " ");
+  Tokenizer def_words(default_str, " ");
 
-  char *copy1,*copy2;
-  char **words,**defwords;
-  int nfield = tokenize(str,words,copy1);
-  int ndef = tokenize((char *) default_str,defwords,copy2);
+  int nfield = words.count();
 
   // process fields one by one, add to index vector
 
@@ -2472,14 +2472,15 @@ int AtomVec::process_fields(char *str, const char *default_str, Method *method)
   int match;
 
   for (int i = 0; i < nfield; i++) {
+    const std::string & field = words[i];
 
     // find field in master Atom::peratom list
 
     for (match = 0; match < nperatom; match++)
-      if (strcmp(words[i],peratom[match].name) == 0) break;
+      if (field == peratom[match].name) break;
     if (match == nperatom) {
       char str[128];
-      sprintf(str,"Peratom field %s not recognized",words[i]);
+      sprintf(str,"Peratom field %s not recognized", field.c_str());
       error->all(FLERR,str);
     }
     index[i] = match;
@@ -2489,56 +2490,24 @@ int AtomVec::process_fields(char *str, const char *default_str, Method *method)
     for (match = 0; match < i; match++)
       if (index[i] == index[match]) {
         char str[128];
-        sprintf(str,"Peratom field %s is repeated",words[i]);
+        sprintf(str,"Peratom field %s is repeated", field.c_str());
         error->all(FLERR,str);
       }
 
     // error if field is in default str
 
-    for (match = 0; match < ndef; match++)
-      if (strcmp(words[i],defwords[match]) == 0) {
+    for (auto & def_field : def_words)
+      if (def_field == field) {
         char str[128];
-        sprintf(str,"Peratom field %s is a default",words[i]);
+        sprintf(str,"Peratom field %s is a default", field.c_str());
         error->all(FLERR,str);
       }
-
   }
 
-  delete [] copy1;
-  delete [] copy2;
-  delete [] words;
-  delete [] defwords;
-
   method->index = index;
   return nfield;
 }
 
-/* ----------------------------------------------------------------------
-   tokenize str into white-space separated words
-   return nwords = number of words
-   return words = vector of ptrs to each word
-   also return copystr since words points into it, caller will delete copystr
-------------------------------------------------------------------------- */
-
-int AtomVec::tokenize(char *str, char **&words, char *&copystr)
-{
-  int n = strlen(str) + 1;
-  copystr = new char[n];
-  strcpy(copystr,str);
-
-  int nword = atom->count_words(copystr);
-  words = new char*[nword];
-
-  nword = 0;
-  char *word = strtok(copystr," ");
-  while (word) {
-    words[nword++] = word;
-    word = strtok(NULL," ");
-  }
-
-  return nword;
-}
-
 /* ----------------------------------------------------------------------
    create a method data structs for processing fields
 ------------------------------------------------------------------------- */
diff --git a/src/atom_vec.h b/src/atom_vec.h
index 46a241becb..eaff9b888a 100644
--- a/src/atom_vec.h
+++ b/src/atom_vec.h
@@ -234,7 +234,6 @@ class AtomVec : protected Pointers {
   int grow_nmax_bonus(int);
   void setup_fields();
   int process_fields(char *, const char *, Method *);
-  int tokenize(char *, char **&, char *&);
   void create_method(int, Method *);
   void init_method(Method *);
   void destroy_method(Method *);
diff --git a/src/atom_vec_hybrid.cpp b/src/atom_vec_hybrid.cpp
index 2f40e10fe3..f08adc41e4 100644
--- a/src/atom_vec_hybrid.cpp
+++ b/src/atom_vec_hybrid.cpp
@@ -17,6 +17,7 @@
 #include "comm.h"
 #include "memory.h"
 #include "error.h"
+#include "tokenizer.h"
 
 using namespace LAMMPS_NS;
 
@@ -513,15 +514,15 @@ char *AtomVecHybrid::merge_fields(int inum, char *root,
 
   // identify unique words in concatenated string
 
-  char *copystr;
-  char **words;
-  int nwords = tokenize(concat,words,copystr);
+  Tokenizer words(concat, " ");
+  int nwords = words.count();
+  
   int *unique = new int[nwords];
 
   for (int i = 0; i < nwords; i++) {
     unique[i] = 1;
     for (int j = 0; j < i; j++)
-      if (strcmp(words[i],words[j]) == 0) unique[i] = 0;
+      if (words[i] == words[j]) unique[i] = 0;
   }
 
   // construct a new deduped string
@@ -531,7 +532,7 @@ char *AtomVecHybrid::merge_fields(int inum, char *root,
 
   for (int i = 0; i < nwords; i++) {
     if (!unique[i]) continue;
-    strcat(dedup,words[i]);
+    strcat(dedup,words[i].c_str());
     if (i < nwords-1) strcat(dedup," ");
   }
 
@@ -542,8 +543,6 @@ char *AtomVecHybrid::merge_fields(int inum, char *root,
 
   // clean up
 
-  delete [] copystr;
-  delete [] words;
   delete [] unique;
 
   // return final concatenated, deduped string