diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c8b10ab7..f9306bce 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -23,11 +23,11 @@ jobs:
 
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12"]
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
         os: [ubuntu-latest]
         jax-version: ["newest"]
         include:
-          - python-version: "3.9"
+          - python-version: "3.10"
             os: "ubuntu-latest"
             jax-version: "0.4.27"  # Keep this in sync with version in requirements.txt
           - python-version: "3.13"
diff --git a/requirements/requirements-test.txt b/requirements/requirements-test.txt
index 035bfac1..3f597eb0 100644
--- a/requirements/requirements-test.txt
+++ b/requirements/requirements-test.txt
@@ -1,3 +1,2 @@
-cloudpickle==2.2.0
-# dm-tree is not compatible with Python 3.13.
-dm-tree>=0.1.5; python_version < "3.13"
+cloudpickle==3.1.0
+dm-tree>=0.1.9
diff --git a/test.sh b/test.sh
index 5c3f9611..b093d201 100755
--- a/test.sh
+++ b/test.sh
@@ -50,13 +50,14 @@ flake8 `find chex -name '*.py' | xargs` --count --select=E9,F63,F7,F82,E225,E251
 PYLINT_ARGS="-efail -wfail -cfail -rfail"
 # Download Google OSS config.
 wget -nd -v -t 3 -O .pylintrc https://google.github.io/styleguide/pylintrc
+# Enforce two space indent style.
+sed -i "s/indent-string.*/indent-string='  '/" .pylintrc
 # Append specific config lines.
-echo "signature-mutators=toolz.functoolz.curry" >> .pylintrc
 echo "disable=unnecessary-lambda-assignment,use-dict-literal" >> .pylintrc
 # Lint modules and tests separately.
 pylint --rcfile=.pylintrc `find chex -name '*.py' | grep -v 'test.py' | xargs` -d E1102|| pylint-exit $PYLINT_ARGS $?
 # Disable `protected-access` warnings for tests.
-pylint --rcfile=.pylintrc `find chex -name '*_test.py' | xargs` -d W0212,E1130,E1102 || pylint-exit $PYLINT_ARGS $?
+pylint --rcfile=.pylintrc `find chex -name '*_test.py' | xargs` -d W0212,E1130,E1102,E1120 || pylint-exit $PYLINT_ARGS $?
 # Cleanup.
 rm .pylintrc