diff --git a/tests/unit/sqlalchemy/test_dialect.py b/tests/unit/sqlalchemy/test_dialect.py
index 413a6bb0..7fd021f2 100644
--- a/tests/unit/sqlalchemy/test_dialect.py
+++ b/tests/unit/sqlalchemy/test_dialect.py
@@ -298,6 +298,23 @@ def test_trino_connection_certificate_auth():
     assert cparams['auth']._key == key
 
 
+def test_trino_connection_certificate_auth_cert_and_key_required():
+    dialect = TrinoDialect()
+    cert = '/path/to/cert.pem'
+    key = '/path/to/key.pem'
+    url = make_url(f'trino://host/?cert={cert}')
+    _, cparams = dialect.create_connect_args(url)
+
+    assert 'http_scheme' not in cparams
+    assert 'auth' not in cparams
+
+    url = make_url(f'trino://host/?key={key}')
+    _, cparams = dialect.create_connect_args(url)
+
+    assert 'http_scheme' not in cparams
+    assert 'auth' not in cparams
+
+
 def test_trino_connection_oauth2_auth():
     dialect = TrinoDialect()
     url = make_url('trino://host/?externalAuthentication=true')
diff --git a/trino/sqlalchemy/dialect.py b/trino/sqlalchemy/dialect.py
index edcc372c..cc3c313d 100644
--- a/trino/sqlalchemy/dialect.py
+++ b/trino/sqlalchemy/dialect.py
@@ -131,7 +131,7 @@ def create_connect_args(self, url: URL) -> Tuple[Sequence[Any], Mapping[str, Any
             kwargs["http_scheme"] = "https"
             kwargs["auth"] = JWTAuthentication(unquote_plus(url.query["access_token"]))
 
-        if "cert" and "key" in url.query:
+        if "cert" in url.query and "key" in url.query:
             kwargs["http_scheme"] = "https"
             kwargs["auth"] = CertificateAuthentication(unquote_plus(url.query['cert']), unquote_plus(url.query['key']))