diff --git a/tests/unit_tests/analysis/test_es_update.py b/tests/unit_tests/analysis/test_es_update.py
index 7284b108b39..19c59f624a4 100644
--- a/tests/unit_tests/analysis/test_es_update.py
+++ b/tests/unit_tests/analysis/test_es_update.py
@@ -801,8 +801,9 @@ def g(X):
 
     prior_da = prior.load_parameters(param_group, range(num_ensemble))
     posterior_da = posterior_ens.load_parameters(param_group, range(num_ensemble))
-    # Because of adaptive localization, not all parameters should be updated.
-    # This would fail if with global updates.
+    # Make sure some, but not all parameters were updated.
+    assert not np.allclose(prior_da, posterior_da)
+    # All parameters would be updated with a global update so this would fail.
     assert np.isclose(prior_da, posterior_da).sum() > 0