diff --git a/src/USER-OMP/thr_data.cpp b/src/USER-OMP/thr_data.cpp
index d6830e64bf..069a5fc756 100644
--- a/src/USER-OMP/thr_data.cpp
+++ b/src/USER-OMP/thr_data.cpp
@@ -58,26 +58,31 @@ void ThrData::init_force(int nall, double **f, double **torque,
   vatom_pair=vatom_bond=vatom_angle=vatom_dihed=vatom_imprp=vatom_kspce=NULL;
 
   _f = f + _tid*nall;
-  memset(&(_f[0][0]),0,nall*3*sizeof(double));
+  if (nall > 0)
+    memset(&(_f[0][0]),0,nall*3*sizeof(double));
 
   if (torque) {
     _torque = torque + _tid*nall;
-    memset(&(_torque[0][0]),0,nall*3*sizeof(double));
+    if (nall > 0)
+      memset(&(_torque[0][0]),0,nall*3*sizeof(double));
   } else _torque = NULL;
 
   if (erforce) {
     _erforce = erforce + _tid*nall;
-    memset(&(_erforce[0]),0,nall*sizeof(double));
+    if (nall > 0)
+      memset(&(_erforce[0]),0,nall*sizeof(double));
   } else _erforce = NULL;
 
   if (de) {
     _de = de + _tid*nall;
-    memset(&(_de[0]),0,nall*sizeof(double));
+    if (nall > 0)
+      memset(&(_de[0]),0,nall*sizeof(double));
   } else _de = NULL;
 
   if (drho) {
     _drho = drho + _tid*nall;
-    memset(&(_drho[0]),0,nall*sizeof(double));
+    if (nall > 0)
+      memset(&(_drho[0]),0,nall*sizeof(double));
   } else _drho = NULL;
 }
 
@@ -88,7 +93,8 @@ void ThrData::init_force(int nall, double **f, double **torque,
 void ThrData::init_eam(int nall, double *rho)
 {
   _rho = rho + _tid*nall;
-  memset(_rho, 0, nall*sizeof(double));
+  if (nall > 0)
+    memset(_rho, 0, nall*sizeof(double));
 }
 
 /* ---------------------------------------------------------------------- */
@@ -99,8 +105,10 @@ void ThrData::init_adp(int nall, double *rho, double **mu, double **lambda)
 
   _mu = mu + _tid*nall;
   _lambda = lambda + _tid*nall;
-  memset(&(_mu[0][0]), 0, nall*3*sizeof(double));
-  memset(&(_lambda[0][0]), 0, nall*6*sizeof(double));
+  if (nall > 0) {
+    memset(&(_mu[0][0]), 0, nall*3*sizeof(double));
+    memset(&(_lambda[0][0]), 0, nall*6*sizeof(double));
+  }
 }
 
 /* ---------------------------------------------------------------------- */
@@ -111,8 +119,10 @@ void ThrData::init_cdeam(int nall, double *rho, double *rhoB, double *D_values)
 
   _rhoB = rhoB + _tid*nall;
   _D_values = D_values + _tid*nall;
-  memset(_rhoB, 0, nall*sizeof(double));
-  memset(_D_values, 0, nall*sizeof(double));
+  if (nall > 0) {
+    memset(_rhoB, 0, nall*sizeof(double));
+    memset(_D_values, 0, nall*sizeof(double));
+  }
 }
 
 /* ---------------------------------------------------------------------- */
@@ -122,7 +132,8 @@ void ThrData::init_eim(int nall, double *rho, double *fp)
   init_eam(nall, rho);
 
   _fp = fp + _tid*nall;
-  memset(_fp,0,nall*sizeof(double));
+  if (nall > 0)
+    memset(_fp,0,nall*sizeof(double));
 }
 
 /* ----------------------------------------------------------------------
diff --git a/src/USER-OMP/thr_omp.cpp b/src/USER-OMP/thr_omp.cpp
index 19537868e5..5ae7cc87da 100644
--- a/src/USER-OMP/thr_omp.cpp
+++ b/src/USER-OMP/thr_omp.cpp
@@ -70,55 +70,65 @@ void ThrOMP::ev_setup_thr(int eflag, int vflag, int nall, double *eatom,
   if (thr_style & THR_PAIR) {
     if (eflag & 2) {
       thr->eatom_pair = eatom + tid*nall;
-      memset(&(thr->eatom_pair[0]),0,nall*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->eatom_pair[0]),0,nall*sizeof(double));
     }
     if (vflag & 4) {
       thr->vatom_pair = vatom + tid*nall;
-      memset(&(thr->vatom_pair[0][0]),0,nall*6*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->vatom_pair[0][0]),0,nall*6*sizeof(double));
     }
   }
 
   if (thr_style & THR_BOND) {
     if (eflag & 2) {
       thr->eatom_bond = eatom + tid*nall;
-      memset(&(thr->eatom_bond[0]),0,nall*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->eatom_bond[0]),0,nall*sizeof(double));
     }
     if (vflag & 4) {
       thr->vatom_bond = vatom + tid*nall;
-      memset(&(thr->vatom_bond[0][0]),0,nall*6*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->vatom_bond[0][0]),0,nall*6*sizeof(double));
     }
   }
 
   if (thr_style & THR_ANGLE) {
     if (eflag & 2) {
       thr->eatom_angle = eatom + tid*nall;
-      memset(&(thr->eatom_angle[0]),0,nall*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->eatom_angle[0]),0,nall*sizeof(double));
     }
     if (vflag & 4) {
       thr->vatom_angle = vatom + tid*nall;
-      memset(&(thr->vatom_angle[0][0]),0,nall*6*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->vatom_angle[0][0]),0,nall*6*sizeof(double));
     }
   }
 
   if (thr_style & THR_DIHEDRAL) {
     if (eflag & 2) {
       thr->eatom_dihed = eatom + tid*nall;
-      memset(&(thr->eatom_dihed[0]),0,nall*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->eatom_dihed[0]),0,nall*sizeof(double));
     }
     if (vflag & 4) {
       thr->vatom_dihed = vatom + tid*nall;
-      memset(&(thr->vatom_dihed[0][0]),0,nall*6*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->vatom_dihed[0][0]),0,nall*6*sizeof(double));
     }
   }
 
   if (thr_style & THR_IMPROPER) {
     if (eflag & 2) {
       thr->eatom_imprp = eatom + tid*nall;
-      memset(&(thr->eatom_imprp[0]),0,nall*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->eatom_imprp[0]),0,nall*sizeof(double));
     }
     if (vflag & 4) {
       thr->vatom_imprp = vatom + tid*nall;
-      memset(&(thr->vatom_imprp[0][0]),0,nall*6*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->vatom_imprp[0][0]),0,nall*6*sizeof(double));
     }
   }
 
@@ -126,11 +136,13 @@ void ThrOMP::ev_setup_thr(int eflag, int vflag, int nall, double *eatom,
   if (thr_style & THR_KSPACE) {
     if (eflag & 2) {
       thr->eatom_kspce = eatom + tid*nall;
-      memset(&(thr->eatom_kspce[0]),0,nall*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->eatom_kspce[0]),0,nall*sizeof(double));
     }
     if (vflag & 4) {
       thr->vatom_kspce = vatom + tid*nall;
-      memset(&(thr->vatom_kspce[0][0]),0,nall*6*sizeof(double));
+      if (nall > 0)
+	memset(&(thr->vatom_kspce[0][0]),0,nall*6*sizeof(double));
     }
   }
 #endif