diff --git a/ollama/_types.py b/ollama/_types.py
index 0df0ddb..710c536 100644
--- a/ollama/_types.py
+++ b/ollama/_types.py
@@ -256,7 +256,7 @@ class Message(SubscriptableBaseModel):
   Chat message.
   """
 
-  role: str
+  role: Literal['user', 'assistant', 'system', 'tool']
   "Assumed role of the message. Response messages has role 'assistant' or 'tool'."
 
   content: Optional[str] = None
diff --git a/tests/test_client.py b/tests/test_client.py
index ca29806..8890afd 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -4,16 +4,14 @@ import os
 import re
 import tempfile
 from pathlib import Path
-from typing import Any
 
 import pytest
-from httpx import Response as httpxResponse
 from pydantic import BaseModel, ValidationError
 from pytest_httpserver import HTTPServer, URIPattern
 from werkzeug.wrappers import Request, Response
 
 from ollama._client import CONNECTION_ERROR_MESSAGE, AsyncClient, Client, _copy_tools
-from ollama._types import Image, Message
+from ollama._types import Image
 
 PNG_BASE64 = 'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVR4nGNgYGAAAAAEAAH2FzhVAAAAAElFTkSuQmCC'
 PNG_BYTES = base64.b64decode(PNG_BASE64)
@@ -1183,32 +1181,3 @@ async def test_async_client_connection_error():
   with pytest.raises(ConnectionError) as exc_info:
     await client.show('model')
   assert str(exc_info.value) == 'Failed to connect to Ollama. Please check that Ollama is downloaded, running and accessible. https://ollama.com/download'
-
-
-def test_arbitrary_roles_accepted_in_message():
-  _ = Message(role='somerandomrole', content="I'm ok with you adding any role message now!")
-
-
-def _mock_request(*args: Any, **kwargs: Any) -> Response:
-  return httpxResponse(status_code=200, content="{'response': 'Hello world!'}")
-
-
-def test_arbitrary_roles_accepted_in_message_request(monkeypatch: pytest.MonkeyPatch):
-  monkeypatch.setattr(Client, '_request', _mock_request)
-
-  client = Client()
-
-  client.chat(model='llama3.1', messages=[{'role': 'somerandomrole', 'content': "I'm ok with you adding any role message now!"}, {'role': 'user', 'content': 'Hello world!'}])
-
-
-async def _mock_request_async(*args: Any, **kwargs: Any) -> Response:
-  return httpxResponse(status_code=200, content="{'response': 'Hello world!'}")
-
-
-@pytest.mark.asyncio
-async def test_arbitrary_roles_accepted_in_message_request_async(monkeypatch: pytest.MonkeyPatch):
-  monkeypatch.setattr(AsyncClient, '_request', _mock_request_async)
-
-  client = AsyncClient()
-
-  await client.chat(model='llama3.1', messages=[{'role': 'somerandomrole', 'content': "I'm ok with you adding any role message now!"}, {'role': 'user', 'content': 'Hello world!'}])