diff --git a/gprMax/cmds_singleuse.py b/gprMax/cmds_singleuse.py
index 0207220a..3a24d5cb 100644
--- a/gprMax/cmds_singleuse.py
+++ b/gprMax/cmds_singleuse.py
@@ -90,14 +90,14 @@ class Discretisation(UserObjectSingle):
         super().__init__(**kwargs)
         self.order = 2
 
-    def build(self, G, uip):
+    def build(self, model, uip):
         try:
-            G.dl = np.array(self.kwargs["p1"])
-            G.dx, G.dy, G.dz = self.kwargs["p1"]
+            model.set_grid_discretisation(self.kwargs["p1"])
         except KeyError:
             logger.exception(f"{self.__str__()} discretisation requires a point")
             raise
 
+        G = model.G
         if G.dl[0] <= 0:
             logger.exception(
                 f"{self.__str__()} discretisation requires the "
diff --git a/gprMax/grid/fdtd_grid.py b/gprMax/grid/fdtd_grid.py
index da4ce76e..d51035f8 100644
--- a/gprMax/grid/fdtd_grid.py
+++ b/gprMax/grid/fdtd_grid.py
@@ -59,6 +59,7 @@ class FDTDGrid:
         self.dx = 0.0
         self.dy = 0.0
         self.dz = 0.0
+        self.dl: np.ndarray
         self.dt = 0.0
         self.dt_mod = None  # Time step stability factor
         self.iteration = 0  # Current iteration number
diff --git a/gprMax/model.py b/gprMax/model.py
index 2b373af0..61177b4a 100644
--- a/gprMax/model.py
+++ b/gprMax/model.py
@@ -20,6 +20,7 @@ import datetime
 import itertools
 import logging
 import sys
+from typing import Tuple
 
 import humanize
 import numpy as np
@@ -160,6 +161,10 @@ class Model:
             if grid.snapshots:
                 save_snapshots(grid)
 
+    def set_grid_discretisation(self, point: Tuple[float, float, float]):
+        self.G.dl = np.array(point)
+        self.G.dx, self.G.dy, self.G.dz = point
+
     def solve(self, solver):
         """Solve using FDTD method.