diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8a181988..7e531408 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -33,6 +33,10 @@ jobs:
               run: |
                   ruff format --check .
 
+            - name: Lint with ruff
+              run: |
+                  ruff check .
+
             - name: Check types with mypy
               run: |
                   mypy --no-site-packages --config-file mypy.ini  . | mypy-baseline filter
diff --git a/posthog/__init__.py b/posthog/__init__.py
index d4d62682..8db0ca06 100644
--- a/posthog/__init__.py
+++ b/posthog/__init__.py
@@ -11,8 +11,15 @@
     set_context_session as inner_set_context_session,
     identify_context as inner_identify_context,
 )
-from posthog.feature_flags import InconclusiveMatchError, RequiresServerEvaluation
-from posthog.types import FeatureFlag, FlagsAndPayloads, FeatureFlagResult
+from posthog.feature_flags import (
+    InconclusiveMatchError as InconclusiveMatchError,
+    RequiresServerEvaluation as RequiresServerEvaluation,
+)
+from posthog.types import (
+    FeatureFlag,
+    FlagsAndPayloads,
+    FeatureFlagResult as FeatureFlagResult,
+)
 from posthog.version import VERSION
 
 __version__ = VERSION
diff --git a/posthog/client.py b/posthog/client.py
index 620064f6..6658f88c 100644
--- a/posthog/client.py
+++ b/posthog/client.py
@@ -3,7 +3,7 @@
 import os
 import sys
 from datetime import datetime, timedelta
-from typing import Any, Callable, Dict, Optional, Union
+from typing import Any, Dict, Optional, Union
 from typing_extensions import Unpack
 from uuid import uuid4
 
@@ -60,7 +60,6 @@
     SizeLimitedDict,
     clean,
     guess_timezone,
-    remove_trailing_slash,
     system_context,
 )
 from posthog.version import VERSION
diff --git a/posthog/test/ai/anthropic/test_anthropic.py b/posthog/test/ai/anthropic/test_anthropic.py
index 5f65a99e..640d7770 100644
--- a/posthog/test/ai/anthropic/test_anthropic.py
+++ b/posthog/test/ai/anthropic/test_anthropic.py
@@ -1,4 +1,3 @@
-import os
 from unittest.mock import patch
 
 import pytest
diff --git a/posthog/test/ai/langchain/test_callbacks.py b/posthog/test/ai/langchain/test_callbacks.py
index b6e74e6b..b181beec 100644
--- a/posthog/test/ai/langchain/test_callbacks.py
+++ b/posthog/test/ai/langchain/test_callbacks.py
@@ -1716,7 +1716,7 @@ def test_combined_reasoning_and_cache_tokens(mock_client):
 
 
 @pytest.mark.skipif(not OPENAI_API_KEY, reason="OPENAI_API_KEY is not set")
-def test_openai_reasoning_tokens(mock_client):
+def test_openai_reasoning_tokens_o4_mini(mock_client):
     model = ChatOpenAI(
         api_key=OPENAI_API_KEY, model="o4-mini", max_completion_tokens=10
     )
diff --git a/posthog/test/integrations/test_middleware.py b/posthog/test/integrations/test_middleware.py
index 777e13f9..a26c9b30 100644
--- a/posthog/test/integrations/test_middleware.py
+++ b/posthog/test/integrations/test_middleware.py
@@ -235,7 +235,9 @@ def test_sync_middleware_with_filter(self):
         get_response = Mock(return_value=mock_response)
 
         # Create middleware with request filter that filters all requests
-        request_filter = lambda req: False
+        def request_filter(req):
+            return False
+
         middleware = PosthogContextMiddleware.__new__(PosthogContextMiddleware)
         middleware.get_response = get_response
         middleware._is_coroutine = False