diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index fa95ed5..52e0eb3 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -12,29 +12,15 @@ repos:
       - id: debug-statements
       - id: check-yaml
         files: .*\.(yaml|yml)$
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.14.8
+    hooks:
+      - id: ruff-check
+        args: ['--fix', '--unsafe-fixes']
+      - id: ruff-format
   - repo: https://opendev.org/openstack/hacking
     rev: 8.0.0
     hooks:
       - id: hacking
         additional_dependencies: []
         exclude: '^(doc|releasenotes|tools)/.*$'
-  - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.14.5
-    hooks:
-      - id: ruff-check
-        args: ['--fix', '--unsafe-fixes']
-      - id: ruff-format
-  - repo: https://github.com/pre-commit/mirrors-mypy
-    rev: v1.18.2
-    hooks:
-      - id: mypy
-        additional_dependencies: [
-          'types-requests',
-          'types-WebOb>=1.8.0.20250822',
-        ]
-        # keep this in-sync with '[tool.mypy] exclude' in 'pyproject.toml'
-        exclude: |
-          (?x)(
-            doc/.*
-            | releasenotes/.*
-          )
diff --git a/oslo_middleware/healthcheck/__init__.py b/oslo_middleware/healthcheck/__init__.py
index 158baff..f5c6bbc 100644
--- a/oslo_middleware/healthcheck/__init__.py
+++ b/oslo_middleware/healthcheck/__init__.py
@@ -38,7 +38,7 @@ import webob.response
 try:
     import greenlet
 except ImportError:
-    greenlet = None
+    greenlet = None  # type: ignore
 
 from oslo_middleware import base
 from oslo_middleware.exceptions import ConfigInvalid
@@ -418,6 +418,10 @@ Reason
         # `disable_by_file` backends are not enabled at same time.
         self._verify_configured_plugins()
 
+        if ty.TYPE_CHECKING:
+            self._backends: stevedore.NamedExtensionManager[
+                pluginbase.HealthcheckBaseExtension
+            ]
         self._backends = stevedore.NamedExtensionManager(
             self.NAMESPACE,
             self._conf_get('backends'),
@@ -648,7 +652,9 @@ Reason
                     return None
 
         results = [
-            ext.obj.healthcheck(req.server_port) for ext in self._backends
+            ext.obj.healthcheck(req.server_port)
+            for ext in self._backends
+            if ext.obj
         ]
         healthy = self._are_results_healthy(results)
         if req.method == "HEAD":
diff --git a/oslo_middleware/tests/test_entry_points.py b/oslo_middleware/tests/test_entry_points.py
index 53e59eb..0ac261a 100644
--- a/oslo_middleware/tests/test_entry_points.py
+++ b/oslo_middleware/tests/test_entry_points.py
@@ -10,12 +10,14 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-from oslotest import base
+from oslotest import base as test_base
 import stevedore
 from testtools import matchers
 
+from oslo_middleware import base
 
-class TestPasteDeploymentEntryPoints(base.BaseTestCase):
+
+class TestPasteDeploymentEntryPoints(test_base.BaseTestCase):
     def test_entry_points(self):
         factory_classes = {
             'catch_errors': 'CatchErrors',
@@ -27,6 +29,7 @@ class TestPasteDeploymentEntryPoints(base.BaseTestCase):
             'sizelimit': 'RequestBodySizeLimiter',
         }
 
+        em: stevedore.ExtensionManager[base.ConfigurableMiddleware]
         em = stevedore.ExtensionManager('paste.filter_factory')
 
         # Ensure all the factories are defined by their names
@@ -40,6 +43,7 @@ class TestPasteDeploymentEntryPoints(base.BaseTestCase):
             'enable_by_files': 'EnableByFilesHealthcheck',
         }
 
+        em: stevedore.ExtensionManager[base.ConfigurableMiddleware]
         em = stevedore.ExtensionManager('oslo.middleware.healthcheck')
 
         # Ensure all the healthcheck plugins are defined by their names
diff --git a/pyproject.toml b/pyproject.toml
index 44a3a34..d595748 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -78,13 +78,8 @@ python_version = "3.10"
 show_column_numbers = true
 show_error_context = true
 strict = true
-# keep this in-sync with 'mypy.exclude' in '.pre-commit-config.yaml'
-exclude = '''
-(?x)(
-    doc
-    | releasenotes
-  )
-'''
+ignore_missing_imports = true
+exclude = '(?x)(doc | releasenotes)'
 
 [[tool.mypy.overrides]]
 module = ["oslo_middleware.tests.*"]
diff --git a/requirements.txt b/requirements.txt
index 7d97f02..4829346 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,6 +10,6 @@ oslo.i18n>=3.15.3 # Apache-2.0
 oslo.utils>=3.33.0 # Apache-2.0
 pbr>=2.0.0 # Apache-2.0
 statsd>=3.2.1 # MIT
-stevedore>=1.20.0 # Apache-2.0
+stevedore>=5.6.0 # Apache-2.0
 typing-extensions>=4.11.0 # PSF-2.0
 WebOb>=1.8.0 # MIT
diff --git a/tox.ini b/tox.ini
index d770d32..92727c9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,11 +9,26 @@ deps =
 commands = stestr run --slowest {posargs}
 
 [testenv:pep8]
-skip_install = true
+description =
+  Run style checks.
 deps =
   pre-commit
+  {[testenv:mypy]deps}
 commands =
   pre-commit run -a
+  {[testenv:mypy]commands}
+
+[testenv:mypy]
+description =
+  Run type checks.
+deps =
+  {[testenv]deps}
+  mypy
+  types-greenlet
+  types-requests
+  types-WebOb>=1.8.0.20250822
+commands =
+  mypy --cache-dir="{envdir}/mypy_cache" {posargs:oslo_middleware}
 
 [testenv:venv]
 commands = {posargs}