diff --git a/tests/unit/aiplatform/test_language_models.py b/tests/unit/aiplatform/test_language_models.py
index 325a920d8a..3032c19c10 100644
--- a/tests/unit/aiplatform/test_language_models.py
+++ b/tests/unit/aiplatform/test_language_models.py
@@ -1557,7 +1557,7 @@ def test_tune_chat_model(
                 _CHAT_BISON_PUBLISHER_MODEL_DICT
             ),
         ):
-            model = preview_language_models.ChatModel.from_pretrained("chat-bison@001")
+            model = language_models.ChatModel.from_pretrained("chat-bison@001")
 
             default_context = "Default context"
             tuning_job = model.tune_model(
diff --git a/vertexai/language_models/_language_models.py b/vertexai/language_models/_language_models.py
index c27ab74286..ac68a23a28 100644
--- a/vertexai/language_models/_language_models.py
+++ b/vertexai/language_models/_language_models.py
@@ -1338,7 +1338,7 @@ def start_chat(
         )
 
 
-class ChatModel(_ChatModelBase):
+class ChatModel(_ChatModelBase, _TunableChatModelMixin):
     """ChatModel represents a language model that is capable of chat.
 
     Examples::