diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c437f6c..f176b76 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -44,7 +44,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8"]
+        python-version: ["3.8", "3.9", "3.10", "3.11"]
         runs-on: [ubuntu-latest, macos-latest]
 
     steps:
diff --git a/noxfile.py b/noxfile.py
index 1153959..a0edbdc 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -11,7 +11,7 @@
 nox.options.sessions = ["lint", "tests"]
 
 
-@nox.session(python="3.8")
+@nox.session(python=["3.8", "3.9", "3.10", "3.11"])
 def lint(session: nox.Session) -> None:
     """
     Run the linter.
@@ -20,7 +20,7 @@ def lint(session: nox.Session) -> None:
     session.run("pre-commit", "run", "--all-files", *session.posargs)
 
 
-# @nox.session(python="3.8")
+# @nox.session(python=["3.8", "3.9", "3.10", "3.11"])
 # def pylint(session: nox.Session) -> None:
 #     """
 #     Run PyLint.
@@ -31,7 +31,7 @@ def lint(session: nox.Session) -> None:
 #     session.run("pylint", "src", *session.posargs)
 
 
-@nox.session(python="3.8")
+@nox.session(python=["3.8", "3.9", "3.10", "3.11"])
 def tests(session: nox.Session) -> None:
     """
     Run the unit and regular tests.
@@ -40,7 +40,7 @@ def tests(session: nox.Session) -> None:
     session.run("pytest", *session.posargs)
 
 
-@nox.session(python="3.8")
+@nox.session(python=["3.8", "3.9", "3.10", "3.11"])
 def coverage(session: nox.Session) -> None:
     """
     Run tests and compute coverage.
@@ -50,7 +50,7 @@ def coverage(session: nox.Session) -> None:
     tests(session)
 
 
-@nox.session(python="3.8")
+@nox.session(python=["3.8", "3.9", "3.10", "3.11"])
 def docs(session: nox.Session) -> None:
     """
     Build the docs. Pass "--serve" to serve.
@@ -69,7 +69,7 @@ def docs(session: nox.Session) -> None:
         session.run("python", "-m", "http.server", "8000", "-d", "_build/html")
 
 
-@nox.session(python="3.8")
+@nox.session(python=["3.8", "3.9", "3.10", "3.11"])
 def build_api_docs(session: nox.Session) -> None:
     """
     Build (regenerate) API docs.
@@ -88,7 +88,7 @@ def build_api_docs(session: nox.Session) -> None:
     )
 
 
-@nox.session(python="3.8")
+@nox.session(python=["3.8", "3.9", "3.10", "3.11"])
 def build(session: nox.Session) -> None:
     """
     Build an SDist and wheel.
diff --git a/pyproject.toml b/pyproject.toml
index 31e929a..88c9bae 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,7 +13,7 @@ authors = [
 ]
 description = "Path signatures for Natural Language Processing."
 readme = "README.md"
-requires-python = ">=3.8, <3.9"
+requires-python = ">=3.8, <3.12"
 classifiers = [
   "Development Status :: 1 - Planning",
   "Intended Audience :: Science/Research",
@@ -24,6 +24,9 @@ classifiers = [
   "Programming Language :: Python :: 3",
   "Programming Language :: Python :: 3 :: Only",
   "Programming Language :: Python :: 3.8",
+  "Programming Language :: Python :: 3.9",
+  "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
   "Topic :: Scientific/Engineering",
 ]
 dynamic = ["version"]
@@ -77,6 +80,7 @@ addopts = ["-ra", "--showlocals", "--strict-markers", "--strict-config"]
 xfail_strict = true
 filterwarnings = [
     "error",
+    "ignore::UserWarning",
     "ignore:Tensorflow not installed; ParametricUMAP will be unavailable:ImportWarning", # umap
     "ignore:pkg_resources is deprecated as an API:DeprecationWarning", # umap
     "ignore:Deprecated call to *:DeprecationWarning",