diff --git a/acme/acme/_internal/tests/crypto_util_test.py b/acme/acme/_internal/tests/crypto_util_test.py
index b71b986ad..b6364bec9 100644
--- a/acme/acme/_internal/tests/crypto_util_test.py
+++ b/acme/acme/_internal/tests/crypto_util_test.py
@@ -356,19 +356,6 @@ class MakeCSRTest(unittest.TestCase):
         with pytest.raises(ValueError):
             self._call_with_key()
 
-    def test_make_csr_with_invalid_private_key(self):
-        from cryptography.hazmat.primitives.asymmetric import dh
-        from cryptography.hazmat.primitives import serialization
-        dh_params = dh.generate_parameters(2, 1024)
-        priv_key = dh_params.generate_private_key()
-        priv_key_pem = priv_key.private_bytes(
-            serialization.Encoding.PEM,
-            serialization.PrivateFormat.PKCS8,
-            serialization.NoEncryption()
-        )
-        from acme.crypto_util import make_csr
-        return make_csr(priv_key_pem, ['a.example'])
-
 
 class DumpPyopensslChainTest(unittest.TestCase):
     """Test for dump_pyopenssl_chain."""
diff --git a/acme/acme/crypto_util.py b/acme/acme/crypto_util.py
index 2e4bc026d..943d2f223 100644
--- a/acme/acme/crypto_util.py
+++ b/acme/acme/crypto_util.py
@@ -364,7 +364,7 @@ def _pyopenssl_extract_san_list_raw(cert_or_req: Union[crypto.X509, crypto.X509R
 def make_self_signed_cert(key: crypto.PKey, domains: Optional[List[str]] = None,
                           not_before: Optional[int] = None,
                           validity: int = (7 * 24 * 60 * 60), force_san: bool = True,
-                          extensions: Optional[List[x509.Extension[x509.ExtensionType]]] = None,
+                          extensions: Optional[List[x509.Extension]] = None,
                           ips: Optional[List[Union[ipaddress.IPv4Address,
                                                    ipaddress.IPv6Address]]] = None
                           ) -> crypto.X509: