diff --git a/src/pretix/base/services/cart.py b/src/pretix/base/services/cart.py
index c015f8baf1..04fbb7e6ac 100644
--- a/src/pretix/base/services/cart.py
+++ b/src/pretix/base/services/cart.py
@@ -945,7 +945,7 @@ class CartManager:
                 continue
             if count < voucher.min_usages_remaining:
                 self._operations = [o for o in self._operations if not (
-                    isinstance(o, self.AddOperation) and o.voucher.pk == voucher.pk
+                    isinstance(o, self.AddOperation) and o.voucher and o.voucher.pk == voucher.pk
                 )]
                 removals = [o.position.pk for o in self._operations if isinstance(o, self.RemoveOperation)]
                 for p in self.positions: