diff --git a/src/compute_sum_atom.cpp b/src/compute_sum_atom.cpp
index a6dd97a7cd..9d20496958 100644
--- a/src/compute_sum_atom.cpp
+++ b/src/compute_sum_atom.cpp
@@ -42,22 +42,30 @@ ComputeSumAtom::ComputeSumAtom(LAMMPS *lmp, int narg, char **arg) :
 
   compute = new Compute*[npre];
 
-  // check consistency of set of pre-computes for scalar & vector output
+  // all sub-computes must be peratom
+  // check consistency of sub-computes for scalar & vector output
 
-  peratom_flag = 1;
-  int icompute = modify->find_compute(id_pre[0]);
-  size_peratom = modify->compute[icompute]->size_peratom;
-
-  for (int i = 1; i < npre; i++) {
+  int icompute;
+  for (int i = 0; i < npre; i++) {
     icompute = modify->find_compute(id_pre[i]);
     if (icompute < 0)
       error->all("Could not find compute sum/atom pre-compute ID");
     if (modify->compute[icompute]->peratom_flag == 0)
-      error->all("Compute sum/atom compute does not compute vector per atom");
-    if (modify->compute[icompute]->size_peratom != size_peratom)
-      error->all("Inconsistent sizes of compute sum/atom compute vectors");
+      error->all("Compute sum/atom compute is not a per-atom compute");
   }
 
+  peratom_flag = 1;
+  icompute = modify->find_compute(id_pre[0]);
+  size_peratom = modify->compute[icompute]->size_peratom;
+
+  for (int i = 1; i < npre; i++) {
+    icompute = modify->find_compute(id_pre[i]);
+    if (modify->compute[icompute]->size_peratom != size_peratom)
+      error->all("Inconsistent sizes of compute sum/atom compute quantities");
+  }
+
+  // values generated by this compute
+
   nmax = 0;
   s_value = NULL;
   v_value = NULL;
diff --git a/src/fix_ave_atom.cpp b/src/fix_ave_atom.cpp
index 3ec3440cd9..9fa515e8e4 100644
--- a/src/fix_ave_atom.cpp
+++ b/src/fix_ave_atom.cpp
@@ -115,7 +115,8 @@ int FixAveAtom::setmask()
 
 void FixAveAtom::init()
 {
-  // set ptrs to one or more computes called each end-of-step
+  // set ptrs to compute and its pre-computes called each end-of-step
+  // put pre-computes in list before compute
 
   int icompute = modify->find_compute(id_compute);
   if (icompute < 0) error->all("Compute ID for fix ave/atom does not exist");
diff --git a/src/fix_ave_spatial.cpp b/src/fix_ave_spatial.cpp
index ba2559aec5..f4d10b32d6 100644
--- a/src/fix_ave_spatial.cpp
+++ b/src/fix_ave_spatial.cpp
@@ -285,7 +285,8 @@ void FixAveSpatial::init()
       error->all("Fix ave/spatial settings invalid with changing box");
   }
 
-  // set ptrs to one or more computes called each end-of-step
+  // set ptrs to compute and its pre-computes called each end-of-step
+  // put pre-computes in list before compute
 
   if (which == COMPUTE) {
     int icompute = modify->find_compute(id_compute);
diff --git a/src/fix_ave_time.cpp b/src/fix_ave_time.cpp
index e7bd6ffdfd..1f10068ddc 100644
--- a/src/fix_ave_time.cpp
+++ b/src/fix_ave_time.cpp
@@ -230,7 +230,8 @@ int FixAveTime::setmask()
 
 void FixAveTime::init()
 {
-  // set ptrs to one or more computes called each end-of-step
+  // set ptrs to compute and its pre-computes called each end-of-step
+  // put pre-computes in list before compute
 
   if (which == COMPUTE) {
     int icompute = modify->find_compute(id);
diff --git a/src/style.h b/src/style.h
index d37d050c97..c1be5c0330 100644
--- a/src/style.h
+++ b/src/style.h
@@ -86,6 +86,7 @@ CommandStyle(write_restart,WriteRestart)
 #include "compute_rotate_dipole.h"
 #include "compute_rotate_gran.h"
 #include "compute_stress_atom.h"
+#include "compute_sum.h"
 #include "compute_sum_atom.h"
 #include "compute_temp.h"
 #include "compute_temp_deform.h"
@@ -107,6 +108,7 @@ ComputeStyle(pressure,ComputePressure)
 ComputeStyle(rotate/dipole,ComputeRotateDipole)
 ComputeStyle(rotate/gran,ComputeRotateGran)
 ComputeStyle(stress/atom,ComputeStressAtom)
+ComputeStyle(sum,ComputeSum)
 ComputeStyle(sum/atom,ComputeSumAtom)
 ComputeStyle(temp,ComputeTemp)
 ComputeStyle(temp/deform,ComputeTempDeform)
diff --git a/src/style_kspace.h b/src/style_kspace.h
index 8c7244afb9..313bef990a 100644
--- a/src/style_kspace.h
+++ b/src/style_kspace.h
@@ -28,6 +28,7 @@ KSpaceStyle(pppm/tip4p,PPPMTIP4P)
 #include "pair_coul_long.h"
 #include "pair_lj_cut_coul_long.h"
 #include "pair_lj_cut_coul_long_tip4p.h"
+#include "pair_new.h"
 #include "pair_lj_charmm_coul_long.h"
 #endif
 
@@ -36,5 +37,6 @@ PairStyle(buck/coul/long,PairBuckCoulLong)
 PairStyle(coul/long,PairCoulLong)
 PairStyle(lj/cut/coul/long,PairLJCutCoulLong)
 PairStyle(lj/cut/coul/long/tip4p,PairLJCutCoulLongTIP4P)
+PairStyle(lj/cut/coul/long/tip4p2,PairLJCutCoulLongTIP4P2)
 PairStyle(lj/charmm/coul/long,PairLJCharmmCoulLong)
 #endif
diff --git a/src/thermo.cpp b/src/thermo.cpp
index 1778ab76c4..5cd9951831 100644
--- a/src/thermo.cpp
+++ b/src/thermo.cpp
@@ -793,7 +793,7 @@ void Thermo::addfield(const char *key, FnPtr func, int typeflag)
 
 /* ----------------------------------------------------------------------
    add compute ID to list of Compute objects to call
-   return index of where this Compute is in list
+   return location of where this Compute is in list
    if already in list, do not add, just return index, else add to list
    convert index into which param
      index = 0 -> scalar, index >= 1 -> vector
diff --git a/src/variable.cpp b/src/variable.cpp
index 55563edaed..369e2633a8 100644
--- a/src/variable.cpp
+++ b/src/variable.cpp
@@ -701,7 +701,7 @@ double Variable::evaluate(char *str, Tree *tree)
       modify->compute[icompute]->init();
 
       // call compute_scalar() if index = 0, else compute_vector()
-      // make pre-call to Compute object's pre-compute(s) if defined
+      // if defined, first call Compute object's pre-compute(s)
 
       int index = atoi(arg);
       if (index == 0) {