diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a3b6abc..d806391 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -47,7 +47,7 @@ jobs:
           - { short: linux, name: ubuntu-latest }
           - { short: win, name: windows-latest }
           - { short: macos, name: macos-14 }
-        python-version: ["3.12", "3.13"]
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
 
     steps:
       - uses: actions/checkout@v4
diff --git a/pyproject.toml b/pyproject.toml
index 57a0855..fb353af 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,7 +14,7 @@ readme = "README.md"
 license = "BSD-3-Clause AND PSF-2.0"
 license-files = ["LICENSE.txt"]
 
-requires-python = ">=3.12"
+requires-python = ">=3.10"
 keywords = ["typing", "stub files", "docstings", "numpydoc"]
 classifiers = [
   "Development Status :: 3 - Alpha",
@@ -25,6 +25,8 @@ classifiers = [
   "Programming Language :: Python",
   "Programming Language :: Python :: 3",
   "Programming Language :: Python :: 3 :: Only",
+  "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
   "Programming Language :: Python :: 3.13",
   "Topic :: Software Development :: Code Generators",
@@ -38,6 +40,7 @@ dependencies = [
   "lark >=1.1.9",
   "black >=24.4.2",
   "isort >=5.13.2",
+  "typing_extensions >= 4.5.0"
 ]
 
 [project.optional-dependencies]
diff --git a/src/docstub/_cache.py b/src/docstub/_cache.py
index e7a9f31..4843a1d 100644
--- a/src/docstub/_cache.py
+++ b/src/docstub/_cache.py
@@ -1,10 +1,11 @@
 import logging
 from functools import cached_property
-from typing import Any, Protocol
 
-logger = logging.getLogger(__name__)
+from typing_extensions import Any, Protocol, TypeVar
 
+logger = logging.getLogger(__name__)
 
+T = TypeVar("T")
 CACHE_DIR_NAME = ".docstub_cache"
 
 
@@ -92,7 +93,7 @@ def validate_cache(path):
         raise FileNotFoundError(f"expected '{path}' to contain a '.gitignore' file")
 
 
-class FuncSerializer[T](Protocol):
+class FuncSerializer(Protocol[T]):
     """Defines an interface to serialize and deserialize results of a function.
 
     This interface is used by `FileCache` to cache results of a
diff --git a/tests/test_docs.py b/tests/test_docs.py
index ea64f50..4b65884 100644
--- a/tests/test_docs.py
+++ b/tests/test_docs.py
@@ -70,7 +70,7 @@ def test_command_line_reference(command, name):
     with md_file.open("r") as io:
         md_content = io.read()
 
-    guard_name = f"cli-{name.replace(" ", "-")}"
+    guard_name = f"cli-{name.replace(' ', '-')}"
     regex = rf"<!--- begin {guard_name} --->(.*)<!--- end {guard_name} --->"
     matches = re.findall(regex, md_content, flags=re.DOTALL)
     assert len(matches) == 1