diff --git a/src/comm.cpp b/src/comm.cpp
index 80e5388989..681b54fe97 100644
--- a/src/comm.cpp
+++ b/src/comm.cpp
@@ -1505,15 +1505,26 @@ void Comm::forward_comm_array(int n, double **array)
 }
 
 /* ----------------------------------------------------------------------
-   reverse communication invoked by a Dump
+   communicate inbuf around full ring of processors with messtag
+   nbytes = size of inbuf = n datums, each of size nper bytes
+   use callback() to allow caller to process each proc's inbuf
 ------------------------------------------------------------------------- */
 
-void Comm::ring(int n, int nmax, char *buf, char *bufcopy, int messtag,
+void Comm::ring(int n, int nper, void *inbuf, int messtag,
                 void (*callback)(int, char *))
 {
   MPI_Request request;
   MPI_Status status;
 
+  int nbytes = n*nper;
+  int maxbytes;
+  MPI_Allreduce(&nbytes,&maxbytes,1,MPI_INT,MPI_MAX,world);
+
+  char *buf,*bufcopy;
+  memory->create(buf,maxbytes,"comm:buf");
+  memory->create(bufcopy,maxbytes,"comm:bufcopy");
+  memcpy(buf,inbuf,nbytes);
+
   int next = me + 1;
   int prev = me - 1;
   if (next == nprocs) next = 0;
@@ -1521,14 +1532,17 @@ void Comm::ring(int n, int nmax, char *buf, char *bufcopy, int messtag,
 
   for (int loop = 0; loop < nprocs; loop++) {
     if (me != next) {
-      MPI_Irecv(bufcopy,nmax,MPI_CHAR,prev,messtag,world,&request);
-      MPI_Send(buf,n,MPI_CHAR,next,messtag,world);
+      MPI_Irecv(bufcopy,maxbytes,MPI_CHAR,prev,messtag,world,&request);
+      MPI_Send(buf,nbytes,MPI_CHAR,next,messtag,world);
       MPI_Wait(&request,&status);
-      MPI_Get_count(&status,MPI_CHAR,&n);
-      memcpy(buf,bufcopy,n);
-      callback(n,buf);
+      MPI_Get_count(&status,MPI_CHAR,&nbytes);
+      memcpy(buf,bufcopy,nbytes);
+      callback(nbytes/nper,buf);
     }
   }
+
+  memory->destroy(buf);
+  memory->destroy(bufcopy);
 }
 
 /* ----------------------------------------------------------------------
diff --git a/src/comm.h b/src/comm.h
index 60c8e6c38c..17c8b0ac50 100644
--- a/src/comm.h
+++ b/src/comm.h
@@ -61,8 +61,7 @@ class Comm : protected Pointers {
   virtual void reverse_comm_dump(class Dump *);    // reverse comm from a Dump
   void forward_comm_array(int, double **);         // forward comm of array
 
-  void ring(int, int, char *, char *, int,
-            void (*)(int, char *));                // ring communication
+  void ring(int, int, void *, int, void (*)(int, char *));   // ring comm
 
   virtual void set(int, char **);         // set communication style
   void set_processors(int, char **);      // set 3d processor grid attributes