diff --git a/src/compute_msd.cpp b/src/compute_msd.cpp
index 15df99d9d9..5da652d521 100644
--- a/src/compute_msd.cpp
+++ b/src/compute_msd.cpp
@@ -127,17 +127,7 @@ void ComputeMSD::init()
 
   // nmsd = # of atoms in group
 
-  int *mask = atom->mask;
-  int nlocal = atom->nlocal;
-
-  nmsd = 0;
-  for (int i = 0; i < nlocal; i++)
-    if (mask[i] & groupbit) nmsd++;
-
-  int nmsd_all;
-  MPI_Allreduce(&nmsd,&nmsd_all,1,MPI_INT,MPI_SUM,world);
-  nmsd = nmsd_all;
-
+  nmsd = group->count(igroup);
   masstotal = group->mass(igroup);
 }
 
diff --git a/src/compute_msd.h b/src/compute_msd.h
index 6889fecd55..23930c0b9d 100644
--- a/src/compute_msd.h
+++ b/src/compute_msd.h
@@ -32,7 +32,8 @@ class ComputeMSD : public Compute {
   virtual void compute_vector();
 
  protected:
-  int comflag,nmsd;
+  int comflag;
+  bigint nmsd;
   double masstotal;
   char *id_fix;
   class FixStore *fix;
diff --git a/src/compute_reduce.cpp b/src/compute_reduce.cpp
index fdc3029609..d4bd7e68c5 100644
--- a/src/compute_reduce.cpp
+++ b/src/compute_reduce.cpp
@@ -301,7 +301,7 @@ ComputeReduce::~ComputeReduce()
 
 void ComputeReduce::init()
 {
-  // set indices and check validity of all computes,fixes,variables
+  // set indices of all computes,fixes,variables
 
   for (int m = 0; m < nvalues; m++) {
     if (which[m] == COMPUTE) {