diff --git a/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/async_client.py b/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/async_client.py
index 08197909b217..44ede80d3811 100644
--- a/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/async_client.py
+++ b/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/async_client.py
@@ -244,7 +244,7 @@ async def delete_posix_account(
                 sent along with the request as metadata.
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name])
         if request is not None and has_flattened_params:
@@ -320,7 +320,7 @@ async def delete_ssh_public_key(
                 sent along with the request as metadata.
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name])
         if request is not None and has_flattened_params:
@@ -402,7 +402,7 @@ async def get_login_profile(
 
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name])
         if request is not None and has_flattened_params:
@@ -485,7 +485,7 @@ async def get_ssh_public_key(
 
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name])
         if request is not None and has_flattened_params:
@@ -585,7 +585,7 @@ async def import_ssh_public_key(
 
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([parent, ssh_public_key, project_id])
         if request is not None and has_flattened_params:
@@ -689,7 +689,7 @@ async def update_ssh_public_key(
 
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name, ssh_public_key, update_mask])
         if request is not None and has_flattened_params:
diff --git a/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/client.py b/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/client.py
index f809d26c751c..7f1d4d61a158 100644
--- a/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/client.py
+++ b/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/client.py
@@ -443,7 +443,7 @@ def delete_posix_account(
                 sent along with the request as metadata.
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name])
         if request is not None and has_flattened_params:
@@ -509,7 +509,7 @@ def delete_ssh_public_key(
                 sent along with the request as metadata.
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name])
         if request is not None and has_flattened_params:
@@ -581,7 +581,7 @@ def get_login_profile(
 
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name])
         if request is not None and has_flattened_params:
@@ -654,7 +654,7 @@ def get_ssh_public_key(
 
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name])
         if request is not None and has_flattened_params:
@@ -744,7 +744,7 @@ def import_ssh_public_key(
 
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([parent, ssh_public_key, project_id])
         if request is not None and has_flattened_params:
@@ -838,7 +838,7 @@ def update_ssh_public_key(
 
         """
         # Create or coerce a protobuf request object.
-        # Sanity check: If we got a request object, we should *not* have
+        # Quick check: If we got a request object, we should *not* have
         # gotten any keyword arguments that map to the request.
         has_flattened_params = any([name, ssh_public_key, update_mask])
         if request is not None and has_flattened_params:
diff --git a/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/transports/grpc.py b/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/transports/grpc.py
index 189b60d2ebdc..850cb27e8c54 100644
--- a/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/transports/grpc.py
+++ b/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/transports/grpc.py
@@ -163,8 +163,11 @@ def __init__(
         if not self._grpc_channel:
             self._grpc_channel = type(self).create_channel(
                 self._host,
+                # use the credentials which are saved
                 credentials=self._credentials,
-                credentials_file=credentials_file,
+                # Set ``credentials_file`` to ``None`` here as
+                # the credentials that we saved earlier should be used.
+                credentials_file=None,
                 scopes=self._scopes,
                 ssl_credentials=self._ssl_channel_credentials,
                 quota_project_id=quota_project_id,
diff --git a/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/transports/grpc_asyncio.py b/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/transports/grpc_asyncio.py
index a9d7e2fd94de..cf0ca4be6e7a 100644
--- a/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/transports/grpc_asyncio.py
+++ b/packages/google-cloud-os-login/google/cloud/oslogin_v1/services/os_login_service/transports/grpc_asyncio.py
@@ -208,8 +208,11 @@ def __init__(
         if not self._grpc_channel:
             self._grpc_channel = type(self).create_channel(
                 self._host,
+                # use the credentials which are saved
                 credentials=self._credentials,
-                credentials_file=credentials_file,
+                # Set ``credentials_file`` to ``None`` here as
+                # the credentials that we saved earlier should be used.
+                credentials_file=None,
                 scopes=self._scopes,
                 ssl_credentials=self._ssl_channel_credentials,
                 quota_project_id=quota_project_id,
diff --git a/packages/google-cloud-os-login/tests/unit/gapic/oslogin_v1/test_os_login_service.py b/packages/google-cloud-os-login/tests/unit/gapic/oslogin_v1/test_os_login_service.py
index 126d4feee595..f5c9469f0c73 100644
--- a/packages/google-cloud-os-login/tests/unit/gapic/oslogin_v1/test_os_login_service.py
+++ b/packages/google-cloud-os-login/tests/unit/gapic/oslogin_v1/test_os_login_service.py
@@ -509,21 +509,28 @@ def test_os_login_service_client_client_options_scopes(
 
 
 @pytest.mark.parametrize(
-    "client_class,transport_class,transport_name",
+    "client_class,transport_class,transport_name,grpc_helpers",
     [
-        (OsLoginServiceClient, transports.OsLoginServiceGrpcTransport, "grpc"),
+        (
+            OsLoginServiceClient,
+            transports.OsLoginServiceGrpcTransport,
+            "grpc",
+            grpc_helpers,
+        ),
         (
             OsLoginServiceAsyncClient,
             transports.OsLoginServiceGrpcAsyncIOTransport,
             "grpc_asyncio",
+            grpc_helpers_async,
         ),
     ],
 )
 def test_os_login_service_client_client_options_credentials_file(
-    client_class, transport_class, transport_name
+    client_class, transport_class, transport_name, grpc_helpers
 ):
     # Check the case credentials file is provided.
     options = client_options.ClientOptions(credentials_file="credentials.json")
+
     with mock.patch.object(transport_class, "__init__") as patched:
         patched.return_value = None
         client = client_class(client_options=options, transport=transport_name)
@@ -559,6 +566,75 @@ def test_os_login_service_client_client_options_from_dict():
         )
 
 
+@pytest.mark.parametrize(
+    "client_class,transport_class,transport_name,grpc_helpers",
+    [
+        (
+            OsLoginServiceClient,
+            transports.OsLoginServiceGrpcTransport,
+            "grpc",
+            grpc_helpers,
+        ),
+        (
+            OsLoginServiceAsyncClient,
+            transports.OsLoginServiceGrpcAsyncIOTransport,
+            "grpc_asyncio",
+            grpc_helpers_async,
+        ),
+    ],
+)
+def test_os_login_service_client_create_channel_credentials_file(
+    client_class, transport_class, transport_name, grpc_helpers
+):
+    # Check the case credentials file is provided.
+    options = client_options.ClientOptions(credentials_file="credentials.json")
+
+    with mock.patch.object(transport_class, "__init__") as patched:
+        patched.return_value = None
+        client = client_class(client_options=options, transport=transport_name)
+        patched.assert_called_once_with(
+            credentials=None,
+            credentials_file="credentials.json",
+            host=client.DEFAULT_ENDPOINT,
+            scopes=None,
+            client_cert_source_for_mtls=None,
+            quota_project_id=None,
+            client_info=transports.base.DEFAULT_CLIENT_INFO,
+            always_use_jwt_access=True,
+        )
+
+    # test that the credentials from file are saved and used as the credentials.
+    with mock.patch.object(
+        google.auth, "load_credentials_from_file", autospec=True
+    ) as load_creds, mock.patch.object(
+        google.auth, "default", autospec=True
+    ) as adc, mock.patch.object(
+        grpc_helpers, "create_channel"
+    ) as create_channel:
+        creds = ga_credentials.AnonymousCredentials()
+        file_creds = ga_credentials.AnonymousCredentials()
+        load_creds.return_value = (file_creds, None)
+        adc.return_value = (creds, None)
+        client = client_class(client_options=options, transport=transport_name)
+        create_channel.assert_called_with(
+            "oslogin.googleapis.com:443",
+            credentials=file_creds,
+            credentials_file=None,
+            quota_project_id=None,
+            default_scopes=(
+                "https://www.googleapis.com/auth/cloud-platform",
+                "https://www.googleapis.com/auth/compute",
+            ),
+            scopes=None,
+            default_host="oslogin.googleapis.com",
+            ssl_credentials=None,
+            options=[
+                ("grpc.max_send_message_length", -1),
+                ("grpc.max_receive_message_length", -1),
+            ],
+        )
+
+
 @pytest.mark.parametrize("request_type", [oslogin.DeletePosixAccountRequest, dict,])
 def test_delete_posix_account(request_type, transport: str = "grpc"):
     client = OsLoginServiceClient(