diff --git a/python/egobox/tests/test_gpmix.py b/python/egobox/tests/test_gpmix.py
index 717e6212..770fc7c8 100644
--- a/python/egobox/tests/test_gpmix.py
+++ b/python/egobox/tests/test_gpmix.py
@@ -33,6 +33,12 @@ def test_gpx_kriging(self):
         self.assertAlmostEqual(
             0.0, gpx.predict_var(np.array([[1.1]])).item(), delta=1e-3
         )
+        self.assertAlmostEqual(
+            1.1204, gpx.predict_derivatives(np.array([[1.1]])).item(), delta=1e-3
+        )
+        self.assertAlmostEqual(
+            0.0092, gpx.predict_var_derivatives(np.array([[1.1]])).item(), delta=1e-3
+        )
 
     def test_gpx_save_load(self):
         filename = "gpdump.json"