diff --git a/libs/prebuilt/langgraph/prebuilt/chat_agent_executor.py b/libs/prebuilt/langgraph/prebuilt/chat_agent_executor.py
index d4facdfea..1f0eb67b7 100644
--- a/libs/prebuilt/langgraph/prebuilt/chat_agent_executor.py
+++ b/libs/prebuilt/langgraph/prebuilt/chat_agent_executor.py
@@ -65,7 +65,7 @@ class AgentState(TypedDict):
 
     messages: Annotated[Sequence[BaseMessage], add_messages]
 
-    is_last_step: IsLastStep
+    is_last_step: NotRequired[IsLastStep]
 
     remaining_steps: RemainingSteps
 
@@ -963,3 +963,4 @@ __all__ = [
     "AgentStateWithStructuredResponsePydantic",
 ]
 
+