diff --git a/src/lib/server/shopping/repository.ts b/src/lib/server/shopping/repository.ts
index 81f91dc..5463f6c 100644
--- a/src/lib/server/shopping/repository.ts
+++ b/src/lib/server/shopping/repository.ts
@@ -87,7 +87,7 @@ export function listShoppingList(
          LOWER(TRIM(COALESCE(i.unit, ''))) AS unit_key,
          MIN(i.name) AS display_name,
          MIN(i.unit) AS display_unit,
-         SUM(i.quantity * cr.servings * 1.0 / COALESCE(r.servings_default, cr.servings)) AS total_quantity,
+         SUM(i.quantity * cr.servings * 1.0 / NULLIF(COALESCE(r.servings_default, cr.servings), 0)) AS total_quantity,
          GROUP_CONCAT(DISTINCT r.title) AS from_recipes,
          EXISTS(
            SELECT 1 FROM shopping_cart_check c
diff --git a/tests/integration/shopping-repository.test.ts b/tests/integration/shopping-repository.test.ts
index 0c33f1a..437b087 100644
--- a/tests/integration/shopping-repository.test.ts
+++ b/tests/integration/shopping-repository.test.ts
@@ -172,4 +172,16 @@ describe('listShoppingList aggregation', () => {
     addRecipeToCart(db, id, null);
     expect(listShoppingList(db).uncheckedCount).toBe(2);
   });
+
+  it('does not blow up when servings_default is zero (silent NULL total_quantity)', () => {
+    const db = openInMemoryForTest();
+    const id = insertRecipe(db, recipe({
+      servings_default: 0,
+      ingredients: [{ position: 1, quantity: 100, unit: 'g', name: 'Mehl', note: null, raw_text: '', section_heading: null }]
+    }));
+    addRecipeToCart(db, id, null, 4);
+    const rows = listShoppingList(db).rows;
+    expect(rows).toHaveLength(1);
+    expect(rows[0].total_quantity).toBeNull();
+  });
 });