diff --git a/biscuit/apps/alsijil/views.py b/biscuit/apps/alsijil/views.py
index bc00d2538730f8e0d8286e98742b98a2429dba35..9d989b2820f1c6f1e3db7335506e4308e0decc05 100644
--- a/biscuit/apps/alsijil/views.py
+++ b/biscuit/apps/alsijil/views.py
@@ -35,7 +35,7 @@ def lesson(request: HttpRequest, week: Optional[int] = None, period_id: Optional
 
     context['lesson_period'] = lesson_period
     context['week'] = wanted_week
-    context['day'] = week_days(wanted_week)[lesson_period.period.weekday]
+    context['day'] = week_days(wanted_week)[lesson_period.period.weekday - 1]
 
     # Create or get lesson documentation object; can be empty when first opening lesson
     lesson_documentation, created = LessonDocumentation.objects.get_or_create(