--- a/test/svg/test_svg.py
+++ b/test/svg/test_svg.py
@@ -30,7 +30,7 @@
 
 class TestUnits:
     @pytest.mark.parametrize(
-        "name", [pytest.param(name, id=name) for name in fpdf.svg.relative_length_units]
+        "name", [pytest.param(name, id=name) for name in sorted(fpdf.svg.relative_length_units)]
     )
     def test_resolve_relative_length_units(self, name):
         with pytest.raises(ValueError):