diff --git a/hnn_core/parallel_backends.py b/hnn_core/parallel_backends.py
index 3dda3b7cc..4016c95c8 100644
--- a/hnn_core/parallel_backends.py
+++ b/hnn_core/parallel_backends.py
@@ -649,7 +649,8 @@ def __init__(self, n_procs=None, mpi_cmd='mpiexec'):
                          'mpi_child.py')
 
         # Split the command into shell arguments for passing to Popen
-        self.mpi_cmd = shlex.split(self.mpi_cmd, posix=sys.platform != 'win32')
+        use_posix = True if sys.platform != 'win32' else False
+        self.mpi_cmd = shlex.split(self.mpi_cmd, posix=use_posix)
 
     def __enter__(self):
         global _BACKEND