diff --git a/ca/ca/test_settings.py b/ca/ca/test_settings.py
index f67a3aa34..97bd7b569 100644
--- a/ca/ca/test_settings.py
+++ b/ca/ca/test_settings.py
@@ -141,6 +141,7 @@
     # 'django.contrib.admindocs',
     "django_object_actions",
     "django_ca",
+    "ninja",
 )
 
 TEMPLATES = [
diff --git a/ca/django_ca/api/endpoints.py b/ca/django_ca/api/endpoints.py
index 7c1ce8d3c..9654416ab 100644
--- a/ca/django_ca/api/endpoints.py
+++ b/ca/django_ca/api/endpoints.py
@@ -40,7 +40,6 @@
 from django_ca.models import Certificate, CertificateAuthority
 from django_ca.profiles import profiles
 from django_ca.querysets import CertificateAuthorityQuerySet, CertificateQuerySet
-from django_ca.typehints import ExtensionDict
 
 api = NinjaAPI(title="django-ca API", version=__version__, urls_namespace="django_ca:api")
 
@@ -94,14 +93,15 @@ def sign_certificate(request: WSGIRequest, serial: str, data: SignCertificateSch
     profile = profiles[data.profile]
     subject = x509.Name.from_rfc4514_string(data.subject)
     algorithm = expires = None
+    extensions: List[x509.Extension[x509.ExtensionType]] = []
+
     if data.algorithm is not None:
         algorithm = constants.HASH_ALGORITHM_TYPES[data.algorithm]()
     if data.expires is not None:
         expires = data.expires
     if data.extensions is not None:
-        extensions: List[x509.Extension[x509.ExtensionType]] = []
         for key, extension_data in data.extensions.items():
-            extensions.append(parse_extension(key, extension_data.dict()))
+            extensions.append(parse_extension(key, extension_data.dict()))  # type: ignore[arg-type]
 
     cert = Certificate.objects.create_cert(
         ca,
diff --git a/ca/django_ca/api/schemas.py b/ca/django_ca/api/schemas.py
index 01d5fe23b..e1f8ed6b8 100644
--- a/ca/django_ca/api/schemas.py
+++ b/ca/django_ca/api/schemas.py
@@ -29,6 +29,8 @@
 
 
 class SubjectAlternativeNameSchema(Schema):
+    """Schema for a Subject Alternative Name extension."""
+
     critical: bool = constants.EXTENSION_DEFAULT_CRITICAL[ExtensionOID.SUBJECT_ALTERNATIVE_NAME]
     value: List[str]
 
diff --git a/ca/django_ca/tests/api/test_sign_cert.py b/ca/django_ca/tests/api/test_sign_cert.py
index 216283e5d..3a8ea026e 100644
--- a/ca/django_ca/tests/api/test_sign_cert.py
+++ b/ca/django_ca/tests/api/test_sign_cert.py
@@ -141,7 +141,6 @@ def test_sign_certificate_with_extensions(self) -> None:
 
         # Test extensions
         extensions = cert.x509_extensions
-        print(extensions[ExtensionOID.SUBJECT_ALTERNATIVE_NAME])
         self.assertEqual(
             extensions[ExtensionOID.SUBJECT_ALTERNATIVE_NAME],
             self.subject_alternative_name(
diff --git a/ca/django_ca/tests/base/__init__.py b/ca/django_ca/tests/base/__init__.py
index ca3d9bea6..b07b7e24a 100644
--- a/ca/django_ca/tests/base/__init__.py
+++ b/ca/django_ca/tests/base/__init__.py
@@ -384,9 +384,9 @@ def uri(url: str) -> x509.UniformResourceIdentifier:  # just a shortcut
     return x509.UniformResourceIdentifier(url)
 
 
-def ip(
+def ip(  # pylint: disable=invalid-name  # just a shortcut
     name: Union[ipaddress.IPv4Address, ipaddress.IPv6Address, ipaddress.IPv4Network, ipaddress.IPv6Network]
-) -> x509.IPAddress:  # just a shortcut
+) -> x509.IPAddress:
     """Shortcut to get a :py:class:`cg:cryptography.x509.IPAddress`."""
     return x509.IPAddress(name)
 
diff --git a/docs/Makefile b/docs/Makefile
index 04f76445c..2ec48f0fb 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -18,7 +18,7 @@ source/_files/docker-compose.yml:
 	cp ../docker-compose.yml source/_files/
 
 source/_files/openapi.json:
-	python ../ca/manage.py export_openapi_schema --api django_ca.api.endpoints.api > source/_files/openapi.json
+	DJANGO_SETTINGS_MODULE=ca.test_settings python ../ca/manage.py export_openapi_schema --api django_ca.api.endpoints.api > source/_files/openapi.json
 
 # Catch-all target: route all unknown targets to Sphinx using the new
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
diff --git a/pyproject.toml b/pyproject.toml
index 34b8a5d0f..d08adbb79 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -126,6 +126,7 @@ module = [
     #   https://github.com/docker/docker-py/issues/2796
     "docker",
     "enchant.tokenize",
+    "httpcore",
     # psycopg and psycopg_c are not installed in isolated mypy envs (tox, ...)
     "psycopg",
     "psycopg_c",