diff --git a/gprMax/config.py b/gprMax/config.py
index d1d5385c..2daacca8 100644
--- a/gprMax/config.py
+++ b/gprMax/config.py
@@ -225,7 +225,7 @@ class SimulationConfig:
             logger.exception("You cannot use both CUDA and OpenCl simultaneously.")
             raise ValueError
 
-        if self.mpi and self.args.subgrid:
+        if self.mpi and hasattr(self.args, "subgrid") and self.args.subgrid:
             logger.exception("You cannot use subgrids with MPI.")
             raise ValueError