diff --git a/tests/test_server.py b/tests/test_server.py
index d4d1224..8935161 100644
--- a/tests/test_server.py
+++ b/tests/test_server.py
@@ -39,7 +39,7 @@ async def authenticated_client(test_client, test_session, sample_api_key_data):
 class TestHealthEndpoints:
     """Tests for health and system endpoints."""
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_health_endpoint(self, test_client):
         """Test health check endpoint."""
         response = await test_client.get("/health")
@@ -54,7 +54,7 @@ class TestHealthEndpoints:
         assert "active_keys" in data
         assert "total_cache_entries" in data
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_metrics_endpoint(self, test_client):
         """Test metrics endpoint."""
         response = await test_client.get("/metrics")
@@ -74,7 +74,7 @@ class TestHealthEndpoints:
 class TestAPIKeyManagement:
     """Tests for API key management endpoints."""
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_create_api_key(self, test_client, sample_api_key_data):
         """Test API key creation."""
         response = await test_client.post(
@@ -90,7 +90,7 @@ class TestAPIKeyManagement:
         assert data["monthly_limit"] == sample_api_key_data["monthly_limit"]
         assert data["is_active"] is True
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_create_duplicate_api_key(self, test_client, test_session, sample_api_key_data):
         """Test creating duplicate API key fails."""
         # Create first key
@@ -119,7 +119,7 @@ class TestAPIKeyManagement:
 class TestRentcastProxyEndpoints:
     """Tests for Rentcast API proxy endpoints."""
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_properties_endpoint_no_auth(self, test_client):
         """Test properties endpoint without authentication."""
         response = await test_client.get("/api/v1/properties")
@@ -127,7 +127,7 @@ class TestRentcastProxyEndpoints:
         assert response.status_code == 401
         assert "Valid API key required" in response.json()["detail"]
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     @patch('httpx.AsyncClient.get')
     async def test_properties_endpoint_success(self, mock_get, authenticated_client):
         """Test successful properties endpoint call."""
@@ -165,7 +165,7 @@ class TestRentcastProxyEndpoints:
         assert response.headers["X-Cache-Hit"] == "False"  # First request
         assert "X-Response-Time-MS" in response.headers
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     @patch('httpx.AsyncClient.get')
     async def test_properties_endpoint_cache_hit(self, mock_get, authenticated_client, test_session):
         """Test cache hit on second request."""
@@ -191,7 +191,7 @@ class TestRentcastProxyEndpoints:
         # Should have called Rentcast API only once
         assert mock_get.call_count == 1
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     @patch('httpx.AsyncClient.get')
     async def test_value_estimate_endpoint(self, mock_get, authenticated_client):
         """Test value estimate endpoint."""
@@ -221,7 +221,7 @@ class TestRentcastProxyEndpoints:
         assert data["estimate"]["value"] == 450000
         assert "X-Estimated-Cost" in response.headers
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_force_refresh_parameter(self, authenticated_client):
         """Test force refresh parameter bypasses cache."""
         # This would need more complex mocking to test properly
@@ -238,7 +238,7 @@ class TestRentcastProxyEndpoints:
 class TestRateLimiting:
     """Tests for rate limiting functionality."""
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_rate_limit_headers(self, test_client):
         """Test that rate limit headers are present."""
         # Make multiple requests to trigger rate limiting
@@ -251,7 +251,7 @@ class TestRateLimiting:
         # Note: This test might need adjustment based on actual rate limits
         assert any(r.status_code == 429 for r in responses[-2:])
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_api_key_usage_tracking(self, authenticated_client, test_session):
         """Test that API key usage is tracked."""
         # Make a request
@@ -275,7 +275,7 @@ class TestRateLimiting:
 class TestCacheManagement:
     """Tests for cache management endpoints."""
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_clear_cache_endpoint(self, test_client):
         """Test cache clearing endpoint."""
         response = await test_client.post(
@@ -289,7 +289,7 @@ class TestCacheManagement:
         assert "message" in data
         assert "cleared" in data["message"].lower()
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_clear_all_cache(self, test_client):
         """Test clearing all cache entries."""
         response = await test_client.post(
@@ -303,7 +303,7 @@ class TestCacheManagement:
 class TestErrorHandling:
     """Tests for error handling."""
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     @patch('httpx.AsyncClient.get')
     async def test_upstream_api_error(self, mock_get, authenticated_client):
         """Test handling of upstream API errors."""
@@ -327,7 +327,7 @@ class TestErrorHandling:
         assert response.status_code == 404
         assert "Upstream API error" in response.json()["detail"]
     
-    @pytest_asyncio.async
+    @pytest.mark.asyncio
     async def test_invalid_parameters(self, authenticated_client):
         """Test validation of invalid parameters."""
         # Test negative limit