diff --git a/light-curve/tests/light_curve_ext/test_feature.py b/light-curve/tests/light_curve_ext/test_feature.py
index 2730269e..661c4a5a 100644
--- a/light-curve/tests/light_curve_ext/test_feature.py
+++ b/light-curve/tests/light_curve_ext/test_feature.py
@@ -426,7 +426,7 @@ def test_bazin_fit_precise(algo):
 @pytest.mark.parametrize("feature", gen_feature_evaluators(parametric_variants=5, rng=0))
 def test_json_serialization(feature):
     n_obs = 128
-    data = gen_lc(n_obs)
+    data = gen_lc(n_obs, rng=0)
     values = feature(*data)
 
     from_to_json = lc.feature_from_json(feature.to_json())