diff --git a/src/pretix/presale/views/__init__.py b/src/pretix/presale/views/__init__.py
index cc0dbc016e..5261894b69 100644
--- a/src/pretix/presale/views/__init__.py
+++ b/src/pretix/presale/views/__init__.py
@@ -158,7 +158,7 @@ def get_cart_total(request):
         else:
             request._cart_total_cache = CartPosition.objects.filter(
                 cart_id=request.session.session_key, event=request.event
-            ).aggregate(sum=Sum('price'))['sum']
+            ).aggregate(sum=Sum('price'))['sum'] or 0
     return request._cart_total_cache
 
 
diff --git a/src/tests/presale/test_checkoutflow.py b/src/tests/presale/test_checkoutflow.py
index 7ec1ca8702..d69294f761 100644
--- a/src/tests/presale/test_checkoutflow.py
+++ b/src/tests/presale/test_checkoutflow.py
@@ -94,8 +94,9 @@ def test_step_ignored(event, mocker, req_with_session):
 
     flow = with_mocked_step(mocker, MockingStep, event)
     req_with_session.event = event
-    assert flow[1].get_next_applicable(req_with_session) is flow[3]
-    assert flow[1] is flow[3].get_prev_applicable(req_with_session)
+    assert flow[1].get_next_applicable(req_with_session) is flow[4]
+    # flow[3] is also skipped because no payment is required if there is no cart
+    assert flow[1] is flow[4].get_prev_applicable(req_with_session)
 
 
 @pytest.mark.django_db