diff --git a/atlas/models.py b/atlas/models.py
index d48ba047..def0a463 100644
--- a/atlas/models.py
+++ b/atlas/models.py
@@ -670,6 +670,7 @@ class Case(models.Model, AuthorMixin, QuestionMixin):
 
     def get_series_blocks(self):
         html = ""
+        s: Series
         for s in self.series.all():
             html += s.get_block()