diff --git a/lib/mobilizon/events/event.ex b/lib/mobilizon/events/event.ex
index f618e1ab2..541c3d4b9 100644
--- a/lib/mobilizon/events/event.ex
+++ b/lib/mobilizon/events/event.ex
@@ -166,6 +166,7 @@ defmodule Mobilizon.Events.Event do
     |> put_picture(attrs)
     |> validate_lengths()
     |> validate_end_time()
+    |> unique_constraint(:url)
   end
 
   @spec validate_lengths(Changeset.t()) :: Changeset.t()