diff --git a/src/main.py b/src/main.py
index c69ac9f..3819c43 100644
--- a/src/main.py
+++ b/src/main.py
@@ -212,7 +212,7 @@ def mark_busy_calendar_slot_by_id(
         description: str | None = None,
         service: Resource = Depends(get_calendar_service)
 ):
-    event = get_slot_by_id(slot_id=slot_id)
+    event = get_slot_by_id(slot_id=slot_id, service=service)
 
     if event.summary != TITLE_FREE:
         raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="Slot is busy")
@@ -232,7 +232,7 @@ def mark_free_calendar_slot_by_id(
         slot_id: str,
         service: Resource = Depends(get_calendar_service)
 ):
-    event = get_slot_by_id(slot_id=slot_id)
+    event = get_slot_by_id(slot_id=slot_id, service=service)
 
     event.summary = TITLE_FREE
     event.colorId = COLOR_FREE