diff --git a/tests/benchmark/conftest.py b/tests/benchmark/conftest.py
index 523acdf..fb03de9 100644
--- a/tests/benchmark/conftest.py
+++ b/tests/benchmark/conftest.py
@@ -1,4 +1,4 @@
-from datetime import UTC, datetime
+from datetime import datetime, timezone
 
 import pytest
 
@@ -22,7 +22,7 @@ def sample_results() -> list[TestResult]:
             passed=True,
             metrics=Metrics(latency_ms=100.0, cost_usd=0.01),
             validation_details={},
-            timestamp=datetime.now(UTC),
+            timestamp=datetime.now(timezone.utc),
         ),
         TestResult(
             test_case=Prompt(
@@ -36,7 +36,7 @@ def sample_results() -> list[TestResult]:
             passed=False,
             metrics=Metrics(latency_ms=150.0, cost_usd=0.02),
             validation_details={},
-            timestamp=datetime.now(UTC),
+            timestamp=datetime.now(timezone.utc),
         ),
         TestResult(
             test_case=Prompt(
@@ -50,7 +50,7 @@ def sample_results() -> list[TestResult]:
             passed=True,
             metrics=Metrics(latency_ms=120.0, cost_usd=0.015),
             validation_details={},
-            timestamp=datetime.now(UTC),
+            timestamp=datetime.now(timezone.utc),
         ),
     ]
 
diff --git a/tests/session/test_runner.py b/tests/session/test_runner.py
index 7db8ccc..173e358 100644
--- a/tests/session/test_runner.py
+++ b/tests/session/test_runner.py
@@ -1,5 +1,5 @@
 import asyncio
-from datetime import UTC
+from datetime import timezone
 from unittest.mock import AsyncMock, MagicMock
 
 import httpx
@@ -25,7 +25,7 @@ async def test_run_single_passing_test(
     assert result.response == "test response"
     assert result.execution_error is None
     assert result.validation_details == {"matched": True}
-    assert result.timestamp.tzinfo == UTC
+    assert result.timestamp.tzinfo == timezone.utc
 
 
 async def test_run_single_failing_validation(