diff --git a/aleksis/apps/chronos/forms.py b/aleksis/apps/chronos/forms.py
index 685f67f7923f64f992822dd2004627adc8ba8760..ab31b103aeccfd231787f82bae36f80eb8586191 100644
--- a/aleksis/apps/chronos/forms.py
+++ b/aleksis/apps/chronos/forms.py
@@ -8,6 +8,8 @@ from aleksis.core.forms import AnnouncementForm
 
 
 class LessonSubstitutionForm(forms.ModelForm):
+    """Form to manage substitutions."""
+
     class Meta:
         model = LessonSubstitution
         fields = ["week", "lesson_period", "subject", "teachers", "room", "cancelled"]