diff --git a/Gemfile b/Gemfile
index 78eb020c..f3799638 100644
--- a/Gemfile
+++ b/Gemfile
@@ -89,7 +89,7 @@ gem 'stackprof'
 gem 'prometheus_exporter'
 
 # debug
-gem 'fast_jsonparser'
+gem 'fast_jsonparser', '~> 0.5.0'
 gem 'down'
 gem 'sourcemap'
 gem 'rack-cors'
diff --git a/app/controllers/api/v1/notices_controller.rb b/app/controllers/api/v1/notices_controller.rb
index cd44130c..436c78b5 100644
--- a/app/controllers/api/v1/notices_controller.rb
+++ b/app/controllers/api/v1/notices_controller.rb
@@ -15,7 +15,7 @@ module Api
                                      params: airbrake_params.to_h
         end
 
-        render status: 201, json: { id: 1, url: root_url }
+        render status: 201, json: { id: 1, url: '' }
       end
 
       private