diff --git a/src/USER-OMP/pair_reaxc_omp.cpp b/src/USER-OMP/pair_reaxc_omp.cpp
index eb3e6c92a0..2f17515130 100644
--- a/src/USER-OMP/pair_reaxc_omp.cpp
+++ b/src/USER-OMP/pair_reaxc_omp.cpp
@@ -97,8 +97,6 @@ PairReaxCOMP::PairReaxCOMP(LAMMPS *lmp) : PairReaxC(lmp), ThrOMP(lmp, THR_PAIR)
 
   num_nbrs_offset = NULL;
 
-  sprintf(fix_id, "REAXC_OMP_%d", Pair::instance_me);
-
 #ifdef OMP_TIMING
   for (int i=0;i<LASTTIMINGINDEX;i++) {
     ompTimingData[i] = 0;
diff --git a/src/USER-OMP/pair_reaxc_omp.h b/src/USER-OMP/pair_reaxc_omp.h
index b831f61f0b..ad8c368aaf 100644
--- a/src/USER-OMP/pair_reaxc_omp.h
+++ b/src/USER-OMP/pair_reaxc_omp.h
@@ -76,7 +76,6 @@ class PairReaxCOMP : public PairReaxC, public ThrOMP {
   }
 
  protected:
-  char fix_id[128];
   virtual void setup();
   virtual void write_reax_atoms();
   virtual int estimate_reax_lists();
diff --git a/src/USER-REAXC/pair_reaxc.cpp b/src/USER-REAXC/pair_reaxc.cpp
index f943715420..8f8dcfb8fc 100644
--- a/src/USER-REAXC/pair_reaxc.cpp
+++ b/src/USER-REAXC/pair_reaxc.cpp
@@ -74,7 +74,8 @@ PairReaxC::PairReaxC(LAMMPS *lmp) : Pair(lmp)
   manybody_flag = 1;
   ghostneigh = 1;
 
-  sprintf(fix_id, "REAXC_%d", Pair::instance_me);
+  fix_id = new char[24];
+  snprintf(fix_id,24,"REAXC_%d",instance_me);
 
   system = (reax_system *)
     memory->smalloc(sizeof(reax_system),"reax:system");
@@ -138,6 +139,7 @@ PairReaxC::~PairReaxC()
   if (copymode) return;
 
   if (fix_reax) modify->delete_fix(fix_id);
+  delete[] fix_id;
 
   if (setup_flag) {
     Close_Output_Files( system, control, out_control, mpi_data );
diff --git a/src/USER-REAXC/pair_reaxc.h b/src/USER-REAXC/pair_reaxc.h
index 5f60abdb67..a833ddbcf0 100644
--- a/src/USER-REAXC/pair_reaxc.h
+++ b/src/USER-REAXC/pair_reaxc.h
@@ -60,7 +60,7 @@ class PairReaxC : public Pair {
   bigint ngroup;
 
  protected:
-  char fix_id[128];
+  char *fix_id;
   double cutmax;
   int nelements;                // # of unique elements
   char **elements;              // names of unique elements