diff --git a/aleksis/core/forms.py b/aleksis/core/forms.py
index 4b166b94c9d99c20da6d23378e7f0bd8bd2d954c..c333ad88e24c8a228774458ea8b66287125da8f6 100644
--- a/aleksis/core/forms.py
+++ b/aleksis/core/forms.py
@@ -191,7 +191,7 @@ class EditTermForm(forms.ModelForm):
         fields = ["caption", "date_start", "date_end"]
 
 
-class AnnouncementForm(forms.ModelForm):
+class AnnouncementForm(ExtensibleForm):
     valid_from = forms.DateTimeField(required=False)
     valid_until = forms.DateTimeField(required=False)