diff --git a/docs/zz.polarization-fit.ipynb b/docs/zz.polarization-fit.ipynb
index 5c8b6ec4..e07dc8bb 100644
--- a/docs/zz.polarization-fit.ipynb
+++ b/docs/zz.polarization-fit.ipynb
@@ -109,9 +109,10 @@
     "# Dalitz variables\n",
     "PHSP = generate_phasespace_sample(DECAY, N_EVENTS, seed=0)\n",
     "# Decay plane variables\n",
-    "PHSP[\"phi\"] = np.random.uniform(-np.pi, +np.pi, N_EVENTS)\n",
-    "PHSP[\"cos_theta\"] = np.random.uniform(-1, +1, N_EVENTS)\n",
-    "PHSP[\"chi\"] = np.random.uniform(-np.pi, +np.pi, N_EVENTS)"
+    "RNG = np.random.default_rng(seed=0)\n",
+    "PHSP[\"phi\"] = RNG.uniform(-np.pi, +np.pi, N_EVENTS)\n",
+    "PHSP[\"cos_theta\"] = RNG.uniform(-1, +1, N_EVENTS)\n",
+    "PHSP[\"chi\"] = RNG.uniform(-np.pi, +np.pi, N_EVENTS)"
    ]
   },
   {