diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index ba3e555..7d24ce5 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -17,7 +17,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13']
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13']
 
     steps:
       - uses: actions/checkout@v4
@@ -75,6 +75,46 @@ jobs:
           cd geoarrow-pandas
           pytest --pyargs geoarrow.pandas --doctest-modules --import-mode=importlib
 
+  # This is a test of geoarrow-types on Python 3.7 (which implies pyarrow 12
+  # since this is the last supported version there). Python 3.7 is still the
+  # runtime available on some hosted platforms (e.g., it is the minimum required
+  # version for apache-sedona Python)
+  oldest-supported:
+    runs-on: ubuntu-latest
+    container:
+      image: python:3.7
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          tags: true
+
+      - name: Check git setup
+        run: |
+          git config --global --add safe.directory "$(pwd)"
+          git describe --long --match='geoarrow-types-*'
+
+      # setuptools_scm available for Python 3.7 does not support version_file
+      # (it can still be installed on Python 3.7, it just can't be built there
+      # without this modification)
+      - name: Patch pyproject.toml
+        run: |
+          cd geoarrow-types
+          sed -i.bak '/^version_file/d' pyproject.toml
+          echo '__version__ = "0.0.0"' > src/geoarrow/types/_version.py
+          echo '__version_tuple__ = (0, 0, 0)' >> src/geoarrow/types/_version.py
+
+      - name: Install (geoarrow-types)
+        run: |
+          pip install --upgrade setuptools setuptools_scm
+          cd geoarrow-types
+          pip install ".[test]"
+
+      - name: Run tests (geoarrow-types)
+        run: |
+          pytest geoarrow-types/tests -v -s
+
   coverage:
     needs: [test]
 
diff --git a/geoarrow-types/pyproject.toml b/geoarrow-types/pyproject.toml
index 0f096d6..03a0d49 100644
--- a/geoarrow-types/pyproject.toml
+++ b/geoarrow-types/pyproject.toml
@@ -22,11 +22,11 @@ dynamic = ["version"]
 description = ""
 authors = [{name = "Dewey Dunnington", email = "dewey@dunnington.ca"}]
 license = {text = "Apache-2.0"}
-requires-python = ">=3.8"
+requires-python = ">=3.7"
 dependencies = []
 
 [project.optional-dependencies]
-test = ["pytest", "pyarrow"]
+test = ["pytest", "pyarrow >= 12", "numpy"]
 
 [project.urls]
 homepage = "https://geoarrow.org"
diff --git a/geoarrow-types/src/geoarrow/types/crs.py b/geoarrow-types/src/geoarrow/types/crs.py
index 4b945c9..520b091 100644
--- a/geoarrow-types/src/geoarrow/types/crs.py
+++ b/geoarrow-types/src/geoarrow/types/crs.py
@@ -1,6 +1,13 @@
 from copy import deepcopy
 import json
-from typing import Union, Mapping, Protocol, Optional
+from typing import Union, Mapping, Optional
+
+try:
+    from typing import Protocol
+except ImportError:
+
+    class Protocol:
+        pass
 
 
 class Crs(Protocol):
diff --git a/geoarrow-types/tests/test_type_pyarrow.py b/geoarrow-types/tests/test_type_pyarrow.py
index 8c0da33..02bbced 100644
--- a/geoarrow-types/tests/test_type_pyarrow.py
+++ b/geoarrow-types/tests/test_type_pyarrow.py
@@ -7,6 +7,10 @@
 
 
 def test_wrap_array_non_exact():
+    pa_version_tuple = tuple(int(component) for component in pa.__version__.split("."))
+    if pa_version_tuple < (14,):
+        pytest.skip("wrap_array with non-exact type requires pyarrow >= 14")
+
     from pyarrow import compute as pc
 
     storage = pc.make_struct(
@@ -448,6 +452,10 @@ def test_roundtrip_extension_type(spec):
 
 
 def test_register_extension_type():
+    pa_version_tuple = tuple(int(component) for component in pa.__version__.split("."))
+    if pa_version_tuple < (14,):
+        pytest.skip("Can't test extension type registration pyarrow < 14")
+
     with type_pyarrow.registered_extension_types():
         schema_capsule = gt.point().to_pyarrow().__arrow_c_schema__()
         pa_type = pa.DataType._import_from_c_capsule(schema_capsule)