diff --git a/src/agenda_culturel/models.py b/src/agenda_culturel/models.py
index 8c0025e..7da13ca 100644
--- a/src/agenda_culturel/models.py
+++ b/src/agenda_culturel/models.py
@@ -1832,7 +1832,7 @@ class Event(models.Model):
 
         # clear cache
         for is_auth in [False, True]:
-            key = make_template_fragment_key("event_body", [is_auth, self])
+            key = make_template_fragment_key("event_body", [is_auth, self.pk])
             cache.delete(key)
 
         # save message if required