diff --git a/python/lammps.py b/python/lammps.py
index c895037c00..62ed272d4b 100644
--- a/python/lammps.py
+++ b/python/lammps.py
@@ -46,17 +46,15 @@ class MPIAbortException(Exception):
   def __str__(self):
     return repr(self.message)
 
-
 class lammps(object):
   
   # detect if Python is using version of mpi4py that can pass a communicator
 
-  has_mpi4py_v2 = False
+  has_mpi4py = False
   try:
     from mpi4py import MPI
     from mpi4py import __version__ as mpi4py_version
-    if mpi4py_version.split('.')[0] == '2':
-      has_mpi4py_v2 = True
+    if mpi4py_version.split('.')[0] in ['2','3']: has_mpi4py = True
   except:
     pass
 
@@ -111,7 +109,9 @@ class lammps(object):
       # need to adjust for type of MPI communicator object
       # allow for int (like MPICH) or void* (like OpenMPI)
 
-      if lammps.has_mpi4py_v2 and comm != None:
+      if comm:
+	if not lammps.has_mpi4py:
+          raise Exception('Python mpi4py version is not 2 or 3')
         if lammps.MPI._sizeof(lammps.MPI.Comm) == sizeof(c_int):
           MPI_Comm = c_int
         else: