diff --git a/notebooks/Koopman-Symbolic.ipynb b/notebooks/Koopman-Symbolic.ipynb
index 622da2f..68d6627 100644
--- a/notebooks/Koopman-Symbolic.ipynb
+++ b/notebooks/Koopman-Symbolic.ipynb
@@ -118,7 +118,7 @@
     "exprs = fhn._exprs\n",
     "x0, x1 = variables\n",
     "basis = generate_monomials(variables, 2)[1:]\n",
-    "lie_obs = ak.core.observables.SymbolicObservable(variables, obs(exprs, basis, variables))"
+    "lie_obs = ak.observable.SymbolicObservable(variables, obs(exprs, basis, variables))"
    ]
   },
   {