diff --git a/src/KSPACE/ewald.cpp b/src/KSPACE/ewald.cpp
index 107dbfbaff..386523c364 100644
--- a/src/KSPACE/ewald.cpp
+++ b/src/KSPACE/ewald.cpp
@@ -354,7 +354,18 @@ void Ewald::compute(int eflag, int vflag)
   if (eflag || vflag) ev_setup(eflag,vflag);
   else evflag = evflag_atom = eflag_global = vflag_global =
          eflag_atom = vflag_atom = 0;
+   
+  // if atom count has changed, update qsum and qsqsum 
 
+  if (atom->natoms != natoms_original) {
+    qsum_qsq();
+    natoms_original = atom->natoms;
+  }
+  
+  // return if there are no charges
+  
+  if (qsqsum == 0.0) return;
+  
   // extend size of per-atom arrays if necessary
 
   if (atom->nlocal > nmax) {
@@ -431,13 +442,6 @@ void Ewald::compute(int eflag, int vflag)
     if (slabflag != 2) f[i][2] += qscale * q[i]*ek[i][2];
   }
 
-  // update qsum and qsqsum, if atom count has changed and energy needed
-
-  if ((eflag_global || eflag_atom) && atom->natoms != natoms_original) {
-    qsum_qsq();
-    natoms_original = atom->natoms;
-  }
-
   // sum global energy across Kspace vevs and add in volume-dependent term
 
   if (eflag_global) {
diff --git a/src/KSPACE/msm.cpp b/src/KSPACE/msm.cpp
index d3c72306be..2719b21e16 100644
--- a/src/KSPACE/msm.cpp
+++ b/src/KSPACE/msm.cpp
@@ -457,6 +457,17 @@ void MSM::compute(int eflag, int vflag)
     }
   }
 
+  // if atom count has changed, update qsum and qsqsum 
+
+  if (atom->natoms != natoms_original) {
+    qsum_qsq();
+    natoms_original = atom->natoms;
+  }
+  
+  // return if there are no charges
+  
+  if (qsqsum == 0.0) return;
+  
   // invoke allocate_peratom() if needed for first time
 
   if (vflag_atom && !peratom_allocate_flag) {
@@ -565,13 +576,6 @@ void MSM::compute(int eflag, int vflag)
 
   if (evflag_atom) fieldforce_peratom();
 
-  // update qsum and qsqsum, if atom count has changed and energy needed
-
-  if ((eflag_global || eflag_atom) && atom->natoms != natoms_original) {
-    qsum_qsq();
-    natoms_original = atom->natoms;
-  }
-
   // sum global energy across procs and add in self-energy term
 
   const double qscale = qqrd2e * scale;
diff --git a/src/KSPACE/pppm.cpp b/src/KSPACE/pppm.cpp
index 814ea1e63e..1924ad4db9 100644
--- a/src/KSPACE/pppm.cpp
+++ b/src/KSPACE/pppm.cpp
@@ -607,6 +607,17 @@ void PPPM::compute(int eflag, int vflag)
     cg_peratom->setup();
   }
 
+  // if atom count has changed, update qsum and qsqsum
+
+  if (atom->natoms != natoms_original) {
+    qsum_qsq();
+    natoms_original = atom->natoms;
+  }
+  
+  // return if there are no charges
+  
+  if (qsqsum == 0.0) return;
+  
   // convert atoms from box to lamda coords
 
   if (triclinic == 0) boxlo = domain->boxlo;
@@ -666,13 +677,6 @@ void PPPM::compute(int eflag, int vflag)
 
   if (evflag_atom) fieldforce_peratom();
 
-  // update qsum and qsqsum, if atom count has changed and energy needed
-
-  if ((eflag_global || eflag_atom) && atom->natoms != natoms_original) {
-    qsum_qsq();
-    natoms_original = atom->natoms;
-  }
-
   // sum global energy across procs and add in volume-dependent term
 
   const double qscale = qqrd2e * scale;