diff --git a/pysr/sr.py b/pysr/sr.py
index 5be8f16e0..1c79425b0 100644
--- a/pysr/sr.py
+++ b/pysr/sr.py
@@ -1587,7 +1587,6 @@ def _run(self, X, y, mutated_params, weights, seed):
             early_stop_condition=early_stop_condition,
             seed=seed,
             deterministic=self.deterministic,
-            extend_user_operators=False,
             define_helper_functions=False,
         )
 
diff --git a/test/test.py b/test/test.py
index cb3067c0f..39ad2ff96 100644
--- a/test/test.py
+++ b/test/test.py
@@ -70,12 +70,13 @@ def test_linear_relation_weighted(self):
         print(model.equations_)
         self.assertLessEqual(model.get_best()["loss"], 1e-4)
 
-    def test_multiprocessing(self):
+    def test_multiprocessing_turbo(self):
         y = self.X[:, 0]
         model = PySRRegressor(
             **self.default_test_kwargs,
             procs=2,
             multithreading=False,
+            turbo=True,
             early_stop_condition="stop_if(loss, complexity) = loss < 1e-4 && complexity == 1",
         )
         model.fit(self.X, y)