diff --git a/drb-c2-core/app/routers/systems.py b/drb-c2-core/app/routers/systems.py
index 6783cfc..4231316 100644
--- a/drb-c2-core/app/routers/systems.py
+++ b/drb-c2-core/app/routers/systems.py
@@ -73,7 +73,7 @@ async def update_system_ai_flags(system_id: str, body: AiFlagsBody):
         raise HTTPException(404, f"System '{system_id}' not found.")
 
     current: dict = existing.get("ai_flags") or {}
-    for field, value in body.model_dump(exclude_unset=False).items():
+    for field, value in body.model_dump(exclude_unset=True).items():
         if value is None:
             current.pop(field, None)   # clear override → inherit global
         else: