diff --git a/app/models/slot.rb b/app/models/slot.rb
index bb5509c..06bcf33 100644
--- a/app/models/slot.rb
+++ b/app/models/slot.rb
@@ -1,4 +1,4 @@
 class Slot < ActiveRecord::Base
   belongs_to :hall
-  belongs_to :event
+  belongs_to :event, required: false
 end