diff --git a/src/KIM/kim_interactions.cpp b/src/KIM/kim_interactions.cpp
index a363978566..ebe6a97fe2 100644
--- a/src/KIM/kim_interactions.cpp
+++ b/src/KIM/kim_interactions.cpp
@@ -73,7 +73,6 @@
 #include "variable.h"
 #include "utils.h"
 #include "fix_store_kim.h"
-#include "fmt/format.h"
 
 extern "C" {
 #include "KIM_SimulatorHeaders.h"
@@ -255,23 +254,33 @@ void KimInteractions::do_setup(int narg, char **arg)
 
 /* ---------------------------------------------------------------------- */
 
-void KimInteractions::KIM_SET_TYPE_PARAMETERS(const std::string &input_line) const
+void KimInteractions::KIM_SET_TYPE_PARAMETERS(char const *const input_line) const
 {
+  char strbuf[MAXLINE];
+  strcpy(strbuf,input_line);
+  char *cmd, *key, *filename;
   int nocomment;
-  auto words = utils::split_words(input_line);
-
-  std::string key = words[1];
-  std::string filename = words[2];
-  std::vector<std::string> species(words.begin()+3,words.end());
-  if (species.size() != atom->ntypes)
-    error->one(FLERR,"Incorrect args for KIM_SET_TYPE_PARAMETERS command");
+  cmd = strtok(strbuf," \t");
+  key = strtok(NULL," \t");
+  filename = strtok(NULL," \t");
 
   FILE *fp;
-  fp = fopen(filename.c_str(),"r");
+  fp = fopen(filename,"r");
   if (fp == NULL) {
     error->one(FLERR,"Parameter file not found");
   }
 
+  char *species1, *species2, *the_rest;
+  std::vector<char *> species;
+  for (int i = 0; i < atom->ntypes; ++i)
+  {
+    char *str;
+    str = strtok(NULL," \t");
+    if (str == NULL)
+      error->one(FLERR,"Incorrect args for KIM_SET_TYPE_PARAMETERS command");
+    species.push_back(str);
+  }
+
   char line[MAXLINE],*ptr;
   int n, eof = 0;
 
@@ -290,29 +299,42 @@ void KimInteractions::KIM_SET_TYPE_PARAMETERS(const std::string &input_line) con
 
     ptr = line;
     nocomment = line[0] != '#';
-    char *species1, *species2, *the_rest;
 
     if(nocomment) {
-      if (key == "pair") {
+      if (strcmp(key,"pair") == 0) {
         species1 = strtok(ptr," \t");
         species2 = strtok(NULL," \t");
         the_rest = strtok(NULL,"\n");
 
-        for (int ia = 0; ia < atom->ntypes; ++ia) {
-          for (int ib = ia; ib < atom->ntypes; ++ib)
-            if (((species[ia] == species1) && (species[ib] == species2))
-                || ((species[ib] == species1) && (species[ia] == species2)))
-              input->one(fmt::format("pair_coeff {} {} {}",ia+1,ib+1,the_rest));
+        for (int type_a = 0; type_a < atom->ntypes; ++type_a) {
+          for (int type_b = type_a; type_b < atom->ntypes; ++type_b) {
+            if(((strcmp(species[type_a],species1) == 0) &&
+                (strcmp(species[type_b],species2) == 0))
+               ||
+               ((strcmp(species[type_b],species1) == 0) &&
+                (strcmp(species[type_a],species2) == 0))
+               ) {
+              char pair_command[MAXLINE];
+              sprintf(pair_command,"pair_coeff %i %i %s",type_a+1,type_b+1,
+                      the_rest);
+              input->one(pair_command);
+            }
+          }
         }
-      } else if (key == "charge") {
+      }
+      else if (strcmp(key,"charge") == 0) {
         species1 = strtok(ptr," \t");
         the_rest = strtok(NULL,"\n");
 
-        for (int ia = 0; ia < atom->ntypes; ++ia) {
-          if (species[ia] == species1)
-            input->one(fmt::format("set type {} charge {}",ia+1,the_rest));
+        for (int type_a = 0; type_a < atom->ntypes; ++type_a) {
+          if(strcmp(species[type_a],species1) == 0) {
+            char pair_command[MAXLINE];
+            sprintf(pair_command,"set type %i charge %s",type_a+1,the_rest);
+            input->one(pair_command);
+          }
         }
-      } else {
+      }
+      else{
         error->one(FLERR,"Unrecognized KEY for KIM_SET_TYPE_PARAMETERS command");
       }
     }
diff --git a/src/KIM/kim_interactions.h b/src/KIM/kim_interactions.h
index 414c7b39d5..0bcfd91307 100644
--- a/src/KIM/kim_interactions.h
+++ b/src/KIM/kim_interactions.h
@@ -77,7 +77,7 @@ class KimInteractions : protected Pointers {
  private:
   void do_setup(int, char **);
   int species_to_atomic_no(const std::string &species) const;
-  void KIM_SET_TYPE_PARAMETERS(const std::string &input_line) const;
+  void KIM_SET_TYPE_PARAMETERS(char const *const input_line) const;
 };
 
 }