diff --git a/ai_ta_backend/flows.py b/ai_ta_backend/flows.py
index 85930650..1f1b42b5 100644
--- a/ai_ta_backend/flows.py
+++ b/ai_ta_backend/flows.py
@@ -36,7 +36,7 @@ def get_users(self, limit: int = 50, pagination: bool = True, api_key: str = "")
 
     return all_users
 
-  def execute_flow(self, hook: str, api_key: str = "", post: str = "", data={}):
+  def execute_flow(self, hook: str, api_key: str = "", post: str = "", data=None) -> None:
     if not api_key:
       raise ValueError('api_key is required')
     headers = {"X-N8N-API-KEY": api_key, "Accept": "application/json"}