diff --git a/pyaviso/engine/etcd_grpc_engine.py b/pyaviso/engine/etcd_grpc_engine.py
index 2e94ded..e071c00 100644
--- a/pyaviso/engine/etcd_grpc_engine.py
+++ b/pyaviso/engine/etcd_grpc_engine.py
@@ -33,7 +33,7 @@ def __init__(self, config: EngineConfig, auth: Auth):
         self._base_url = f"http://{self._host}:{self._port}/v3/"
 
     def _initialise_server(self):
-        if isinstance(self.auth, EtcdAuth):
+        if type(self.auth) == EtcdAuth:  # noqa: E721
             self._server = Etcd3Client(
                 self.host, self.port, user=self.auth.username, password=self.auth.password, timeout=self.timeout
             )
diff --git a/pyaviso/engine/etcd_rest_engine.py b/pyaviso/engine/etcd_rest_engine.py
index 32938e5..8a0c28b 100644
--- a/pyaviso/engine/etcd_rest_engine.py
+++ b/pyaviso/engine/etcd_rest_engine.py
@@ -247,7 +247,7 @@ def _authenticate(self) -> bool:
         This method authenticates  the user and set the internal token, this is only done for Etcd authentication
         :return: True if successfully authenticated
         """
-        if isinstance(self.auth, EtcdAuth):
+        if type(self.auth) == EtcdAuth:  # noqa: E721
             logger.debug(f"Authenticating user {self.auth.username}...")
 
             url = self._base_url + "auth/authenticate"