diff --git a/test/test-suite/test_colour.py b/test/test-suite/test_colour.py
index b8cb0754..b727937b 100644
--- a/test/test-suite/test_colour.py
+++ b/test/test-suite/test_colour.py
@@ -170,6 +170,11 @@ class TestColour:
 
         im = test.colourspace("cmyk").colourspace("srgb")
 
+        before = test(10, 10)
+        after = im(10, 10)
+
+        assert_almost_equal_objects(before, after, threshold=10)
+
 
 if __name__ == '__main__':
     pytest.main()