diff --git a/demo/demo_rayleigh-taylor-instability/demo_raleigh-taylor-instability.py b/demo/demo_rayleigh-taylor-instability/demo_raleigh-taylor-instability.py
index e48c7ed..1202562 100644
--- a/demo/demo_rayleigh-taylor-instability/demo_raleigh-taylor-instability.py
+++ b/demo/demo_rayleigh-taylor-instability/demo_raleigh-taylor-instability.py
@@ -22,13 +22,8 @@ def pprint(*msg, rank=None):
     print(f"[{MPI.COMM_WORLD.rank}]: {' '.join(map(str, msg))}", flush=True)
 
 
-lmbda, H = 0.9142, 1.0
-mesh = dolfinx.mesh.create_rectangle(
-    MPI.COMM_WORLD, [[0.0, 0.0], [lmbda, H]], [40, 40],
-    cell_type=dolfinx.mesh.CellType.triangle,
-    diagonal=dolfinx.mesh.DiagonalType.left_right)
-
 # Parameters
+lmbda, H = 0.9142, 1.0
 p = 2
 A = 0.02
 db = 0.2
@@ -37,6 +32,12 @@ def pprint(*msg, rank=None):
 t_max = 2000.0
 num_t_steps_max = 200
 
+# Geometry
+mesh = dolfinx.mesh.create_rectangle(
+    MPI.COMM_WORLD, [[0.0, 0.0], [lmbda, H]], [40, 40],
+    cell_type=dolfinx.mesh.CellType.triangle,
+    diagonal=dolfinx.mesh.DiagonalType.left_right)
+
 # Chemistry space
 PHI = dolfinx.fem.FunctionSpace(mesh, ("DG", 0))
 phi = dolfinx.fem.Function(PHI)