diff --git a/shopping/db.py b/shopping/db.py
index 6f2f877..b1d9ec2 100644
--- a/shopping/db.py
+++ b/shopping/db.py
@@ -105,7 +105,7 @@ async def purchase(conn, shopping_list: ShoppingList) -> None:
         if item.ingredient_id is None or item.ingredient_id < 0:
             raise ValueError('Ingredient request must have a valid ingredient id')
 
-        isMeal = item.meal_id is None or item.meal_id < 0
+        isMeal = item.meal_id is not None and item.meal_id >= 0
         isPersonRequest = (not isMeal) and item.person_id is not None and item.person_id >= 0
 
         if not isMeal and not isPersonRequest: