diff --git a/lib/redmine_messenger/patches/project_patch.rb b/lib/redmine_messenger/patches/project_patch.rb
index 98dad55..849d071 100644
--- a/lib/redmine_messenger/patches/project_patch.rb
+++ b/lib/redmine_messenger/patches/project_patch.rb
@@ -6,7 +6,7 @@ module RedmineMessenger
       extend ActiveSupport::Concern
 
       included do
-        has_one :messenger_setting
+        has_one :messenger_setting, dependent: :destroy
       end
     end
   end