diff --git a/examples/helloworld/__main__.py b/examples/helloworld/__main__.py
index ac6cca7d..ba06207b 100644
--- a/examples/helloworld/__main__.py
+++ b/examples/helloworld/__main__.py
@@ -27,7 +27,7 @@
         version='1.0.0',
         defaultInputModes=['text'],
         defaultOutputModes=['text'],
-        capabilities=AgentCapabilities(),
+        capabilities=AgentCapabilities(streaming=True),
         skills=[skill],
         authentication=AgentAuthentication(schemes=['public']),
     )
diff --git a/src/a2a/server/agent_execution/context.py b/src/a2a/server/agent_execution/context.py
index 3c61dc6b..870c5f8e 100644
--- a/src/a2a/server/agent_execution/context.py
+++ b/src/a2a/server/agent_execution/context.py
@@ -19,7 +19,7 @@ def __init__(
         task_id: str | None = None,
         context_id: str | None = None,
         task: Task | None = None,
-        related_tasks: list[Task] = None,
+        related_tasks: list[Task] | None = None,
     ):
         if related_tasks is None:
             related_tasks = []
diff --git a/src/a2a/server/events/in_memory_queue_manager.py b/src/a2a/server/events/in_memory_queue_manager.py
index a0d95f8e..9d4a135b 100644
--- a/src/a2a/server/events/in_memory_queue_manager.py
+++ b/src/a2a/server/events/in_memory_queue_manager.py
@@ -18,7 +18,7 @@ class InMemoryQueueManager(QueueManager):
     true scalable deployment.
     """
 
-    def __init__(self):
+    def __init__(self) -> None:
         self._task_queue: dict[str, EventQueue] = {}
         self._lock = asyncio.Lock()