diff --git a/nautilus_trader/live/data_engine.py b/nautilus_trader/live/data_engine.py
index c95f9c214b32..f6f008d6eab1 100644
--- a/nautilus_trader/live/data_engine.py
+++ b/nautilus_trader/live/data_engine.py
@@ -15,6 +15,7 @@
 
 import asyncio
 from asyncio import Queue
+from typing import Final
 
 from nautilus_trader.cache.cache import Cache
 from nautilus_trader.common.clock import LiveClock
@@ -55,7 +56,7 @@ class LiveDataEngine(DataEngine):
 
     """
 
-    _sentinel = None
+    _sentinel: Final[None] = None
 
     def __init__(
         self,
diff --git a/nautilus_trader/live/execution_engine.py b/nautilus_trader/live/execution_engine.py
index 5e958b785337..6b9d7b0c3dec 100644
--- a/nautilus_trader/live/execution_engine.py
+++ b/nautilus_trader/live/execution_engine.py
@@ -17,7 +17,7 @@
 import math
 from asyncio import Queue
 from decimal import Decimal
-from typing import Any
+from typing import Any, Final
 
 from nautilus_trader.cache.cache import Cache
 from nautilus_trader.common.clock import LiveClock
@@ -93,7 +93,7 @@ class LiveExecutionEngine(ExecutionEngine):
 
     """
 
-    _sentinel = None
+    _sentinel: Final[None] = None
 
     def __init__(
         self,
diff --git a/nautilus_trader/live/risk_engine.py b/nautilus_trader/live/risk_engine.py
index 889a65d9ff94..c76ac529a41c 100644
--- a/nautilus_trader/live/risk_engine.py
+++ b/nautilus_trader/live/risk_engine.py
@@ -15,6 +15,7 @@
 
 import asyncio
 from asyncio import Queue
+from typing import Final
 
 from nautilus_trader.cache.base import CacheFacade
 from nautilus_trader.common.clock import LiveClock
@@ -56,7 +57,7 @@ class LiveRiskEngine(RiskEngine):
 
     """
 
-    _sentinel = None
+    _sentinel: Final[None] = None
 
     def __init__(
         self,