diff --git a/colour/colorimetry/tests/test_blackbody.py b/colour/colorimetry/tests/test_blackbody.py
index 775f48e7c..8ae3f346b 100644
--- a/colour/colorimetry/tests/test_blackbody.py
+++ b/colour/colorimetry/tests/test_blackbody.py
@@ -1256,7 +1256,8 @@ def test_nan_planck_law(self):
 
         cases = [-1.0, 0.0, 1.0, -np.inf, np.inf, np.nan]
         cases = np.array(list(set(product(cases, repeat=3))))
-        planck_law(cases, cases)
+        with self.assertRaises(AssertionError):
+            planck_law(cases, cases)
 
 
 class TestSdBlackbody(unittest.TestCase):