diff --git a/backend/thirdparty/zasilkovna/models.py b/backend/thirdparty/zasilkovna/models.py
index 9248775..174911e 100644
--- a/backend/thirdparty/zasilkovna/models.py
+++ b/backend/thirdparty/zasilkovna/models.py
@@ -22,6 +22,7 @@ from django.utils import timezone
 from django.core.validators import RegexValidator
 from django.core.files.base import ContentFile
 from django.apps import apps
+from rest_framework.exceptions import ValidationError
 
 from .client import PacketaAPI