diff --git a/slack_bolt/adapter/aws_lambda/local_lambda_client.py b/slack_bolt/adapter/aws_lambda/local_lambda_client.py
index 82181062e..92abf0c32 100644
--- a/slack_bolt/adapter/aws_lambda/local_lambda_client.py
+++ b/slack_bolt/adapter/aws_lambda/local_lambda_client.py
@@ -14,7 +14,7 @@ def __init__(self, app: Chalice, config: Config) -> None:
 
     def invoke(
         self,
-        FunctionName: str = None,
+        FunctionName: str,
         InvocationType: str = "Event",
         Payload: str = "{}",
     ) -> InvokeResponse:
diff --git a/slack_bolt/middleware/ssl_check/ssl_check.py b/slack_bolt/middleware/ssl_check/ssl_check.py
index 33be2bf63..e02ec7881 100644
--- a/slack_bolt/middleware/ssl_check/ssl_check.py
+++ b/slack_bolt/middleware/ssl_check/ssl_check.py
@@ -1,4 +1,5 @@
-from typing import Callable
+from logging import Logger
+from typing import Callable, Optional
 
 from slack_bolt.logger import get_bolt_logger
 from slack_bolt.middleware.middleware import Middleware
@@ -7,7 +8,10 @@
 
 
 class SslCheck(Middleware):  # type: ignore
-    def __init__(self, verification_token: str = None):
+    verification_token: Optional[str]
+    logger: Logger
+
+    def __init__(self, verification_token: Optional[str] = None):
         """Handles `ssl_check` requests.
         Refer to https://api.slack.com/interactivity/slash-commands for details.