diff --git a/tests/test_views.py b/tests/test_views.py
index 24a9ec2..b59355d 100644
--- a/tests/test_views.py
+++ b/tests/test_views.py
@@ -3,8 +3,8 @@
 from django.test import override_settings
 from django_hearthstone.cards.models import Card
 from shortuuid.main import int_to_string
-
 from tests import settings
+
 from twitch_hdt_ebs.twitch import TwitchClient
 from twitch_hdt_ebs.views import ActiveChannelsView
 
diff --git a/twitch_hdt_ebs/views.py b/twitch_hdt_ebs/views.py
index 1436a77..582b406 100644
--- a/twitch_hdt_ebs/views.py
+++ b/twitch_hdt_ebs/views.py
@@ -331,6 +331,8 @@ def _dbf_id_to_card_id(self, dbf_id) -> str:
 			card = Card.objects.get(dbf_id=dbf_id)
 			card_id = card.card_id
 			self.CARDS_MAP_CACHE[dbf_id] = card.card_id
+
+		assert card_id  # make mypy happy
 		return card_id
 
 	def get_shortid_from_deck_list(