diff --git a/tests/firedrake/regression/test_locate_cell.py b/tests/firedrake/regression/test_locate_cell.py
index 209ab16744..ccd507c875 100644
--- a/tests/firedrake/regression/test_locate_cell.py
+++ b/tests/firedrake/regression/test_locate_cell.py
@@ -163,7 +163,7 @@ def test_high_order_location_quad():
     assert any(c is not None for c in cells)
 
 
-@pytest.mark.parallel([1, 3])
+@pytest.mark.parallel(nprocs=3)
 def test_high_order_location_extruded():
     m = UnitSquareMesh(2, 2)
     mesh = ExtrudedMesh(m, 3)