diff --git a/MODULE.bazel b/MODULE.bazel
index f14196e..5dc95f9 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -3,10 +3,10 @@ module(
 )
 
 # https://registry.bazel.build/modules/abseil-cpp
-bazel_dep(name = "abseil-cpp", version = "20260526.0", repo_name = "com_google_absl")
+bazel_dep(name = "abseil-cpp", version = "20260817.0", repo_name = "com_google_absl")
 single_version_override(
     module_name = "abseil-cpp",
-    version = "20260526.0",
+    version = "20260817.0",
 )
 
 # https://registry.bazel.build/modules/abseil-py
@@ -47,7 +47,11 @@ bazel_dep(name = "pybind11_abseil", version = "202402.0")
 bazel_dep(name = "pybind11_bazel", version = "3.0.0")
 
 # https://registry.bazel.build/modules/rules_cc
-bazel_dep(name = "rules_cc", version = "0.2.16")
+bazel_dep(name = "rules_cc", version = "0.2.18")
+single_version_override(
+    module_name = "rules_cc",
+    version = "0.2.18",
+)
 
 # https://registry.bazel.build/modules/rules_proto
 bazel_dep(name = "rules_proto", version = "7.1.0")
diff --git a/cel_expr_python/cel_env_test.py b/cel_expr_python/cel_env_test.py
index eabe446..3212dc4 100644
--- a/cel_expr_python/cel_env_test.py
+++ b/cel_expr_python/cel_env_test.py
@@ -725,18 +725,18 @@ def test_config_functions_deprecated_syntax(self):
     self.assertFalse(res.value())
 
   def test_env_options(self):
-    options = cel.Options(enable_pratt_parser=True)
+    options = cel.Options()
     self.assertTrue(options.enable_pratt_parser)
     self.assertEqual(repr(options), "Options(enable_pratt_parser=True)")
     options.enable_pratt_parser = False
     self.assertFalse(options.enable_pratt_parser)
     self.assertEqual(repr(options), "Options(enable_pratt_parser=False)")
 
-    env = cel.NewEnv(options=cel.Options(enable_pratt_parser=True))
-    self.assertTrue(env.options().enable_pratt_parser)
+    env = cel.NewEnv(options=cel.Options(enable_pratt_parser=False))
+    self.assertFalse(env.options().enable_pratt_parser)
 
     default_env = cel.NewEnv()
-    self.assertFalse(default_env.options().enable_pratt_parser)
+    self.assertTrue(default_env.options().enable_pratt_parser)
 
 
 class TestCelExtension(cel.CelExtension):
diff --git a/cel_expr_python/cel_test.py b/cel_expr_python/cel_test.py
index 377dadd..c04806f 100644
--- a/cel_expr_python/cel_test.py
+++ b/cel_expr_python/cel_test.py
@@ -1074,8 +1074,8 @@ class CelTest(_CelTestBase):
   pass
 
 
-class CelPrattParserTest(_CelTestBase):
-  options = cel.Options(enable_pratt_parser=True)
+class CelAntlrParserTest(_CelTestBase):
+  options = cel.Options(enable_pratt_parser=False)
 
 
 if __name__ == "__main__":
diff --git a/cel_expr_python/py_cel_options.cc b/cel_expr_python/py_cel_options.cc
index 853c282..8699812 100644
--- a/cel_expr_python/py_cel_options.cc
+++ b/cel_expr_python/py_cel_options.cc
@@ -56,7 +56,7 @@ void PyCelOptions::DefinePythonBindings(pybind11::module& m) {
       .def(py::init([](bool enable_pratt_parser) {
              return PyCelOptions{.enable_pratt_parser = enable_pratt_parser};
            }),
-           py::arg("enable_pratt_parser") = false)
+           py::arg("enable_pratt_parser") = true)
       .def_readwrite("enable_pratt_parser", &PyCelOptions::enable_pratt_parser)
       .def("__repr__", &GenericRepr);
 }
diff --git a/cel_expr_python/py_cel_options.h b/cel_expr_python/py_cel_options.h
index 5aac31c..7268162 100644
--- a/cel_expr_python/py_cel_options.h
+++ b/cel_expr_python/py_cel_options.h
@@ -24,7 +24,7 @@ namespace cel_python {
 struct PyCelOptions {
   static void DefinePythonBindings(pybind11::module& m);
 
-  bool enable_pratt_parser = false;
+  bool enable_pratt_parser = true;
 };
 
 }  // namespace cel_python
diff --git a/conformance/conformance_test.py b/conformance/conformance_test.py
index c3c86c4..da54e88 100644
--- a/conformance/conformance_test.py
+++ b/conformance/conformance_test.py
@@ -91,6 +91,10 @@ class ConformanceTestSuite(unittest.TestSuite):
       "timestamps/timestamp_arithmetic/subtract_max_duration_from_max_time",
       "timestamps/timestamp_range/sub_time_duration_over",
       "timestamps/timestamp_range/sub_time_duration_under",
+      # TODO(b/581943737): These depend on legacy US/ timezones, which are
+      # incompletely supported in our test environment.
+      "timestamps/timestamp_selectors_tz/getDayOfMonth_name_pos",
+      "timestamps/timestamp_selectors_tz/getDayOfYear",
       "wrappers/duration/nanos_over",
       "wrappers/duration/nanos_under",
       "wrappers/duration/negative_seconds_positive_nanos",