diff --git a/Gemfile b/Gemfile
index c1eff29..6441cf8 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,3 @@
 source 'https://rubygems.org'
 
 gem 'slim-rails'
-gem 'validate_url'
diff --git a/app/models/messenger_setting.rb b/app/models/messenger_setting.rb
index 1b4b449..67bb1bc 100644
--- a/app/models/messenger_setting.rb
+++ b/app/models/messenger_setting.rb
@@ -1,7 +1,7 @@
 class MessengerSetting < ActiveRecord::Base
   belongs_to :project
 
-  validates :messenger_url, url: { allow_blank: true, message: l(:error_messenger_invalid_url) }
+  validates :messenger_url, format: { with: URI::DEFAULT_PARSER.make_regexp(%w[http https]), allow_blank: true }
 
   def self.find_or_create(p_id)
     setting = MessengerSetting.find_by project_id: p_id
diff --git a/config/locales/de.yml b/config/locales/de.yml
index adc8cd6..d793788 100644
--- a/config/locales/de.yml
+++ b/config/locales/de.yml
@@ -1,7 +1,6 @@
 # German strings
 de:
   default_mentionsl_info: Benutzer, die immer mit Mentions benachrichtet werden sollen. Mehrere Namen können mit Komma getrennt angegeben werden (z.B. @all, @here).
-  error_messenger_invalid_url: "ist keine gültige URL"
   label_messenger_contact_created: "%{project_url} - Kontakt %{url} erstellt von *%{user}*"
   label_messenger_contact_updated: "%{project_url} - Kontakt %{url} aktualisiert von *%{user}*"
   label_messenger_db_entry_created: "%{project_url} - DB Eintrag %{url} erstellt von *%{user}*"
diff --git a/config/locales/en.yml b/config/locales/en.yml
index e509449..35e6e15 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -1,7 +1,6 @@
 # English strings
 en:
   default_mentionsl_info: Default people to notify, comma separated (e.g. @all, @here)
-  error_messenger_invalid_url: is not a valid URL
   label_messenger_contact_created: "%{project_url} - Contact %{url} created by *%{user}*"
   label_messenger_contact_updated: "%{project_url} - Contact %{url} updated by *%{user}*"
   label_messenger_db_entry_created: "%{project_url} - DB entry %{url} created by *%{user}*"
diff --git a/config/locales/fr.yml b/config/locales/fr.yml
index c102adf..9a0d7f8 100644
--- a/config/locales/fr.yml
+++ b/config/locales/fr.yml
@@ -1,7 +1,6 @@
 # French strings
 fr:
   default_mentionsl_info: Personnes à notifier par défaut, séparées par des virgules (@all, @here)
-  error_messenger_invalid_url: n'est pas une URL valide
   label_messenger_contact_created: "%{project_url} - Le contact %{url} créé par *%{user}*"
   label_messenger_contact_updated: "%{project_url} - Le contact %{url} mis à jour par *%{user}*"
   label_messenger_db_entry_created: "%{project_url} - Entrée de base de données %{url} créée par *%{user}*"
diff --git a/config/locales/ja.yml b/config/locales/ja.yml
index fba67a7..2bf9046 100644
--- a/config/locales/ja.yml
+++ b/config/locales/ja.yml
@@ -1,7 +1,6 @@
 # Japanese strings
 ja:
   default_mentionsl_info: Default people to notify, comma separated (e.g. @all, @here)
-  error_messenger_invalid_url: is not a valid URL
   label_messenger_contact_created: "%{project_url} - コンタクト %{url} が *%{user}* によって作成されました。"
   label_messenger_contact_updated: "%{project_url} - コンタクト %{url} が*%{user}* によって更新されました。"
   label_messenger_db_entry_created: "%{project_url} - DB entry %{url} created by *%{user}*"
diff --git a/config/locales/ko.yml b/config/locales/ko.yml
index fee4783..c03c52f 100644
--- a/config/locales/ko.yml
+++ b/config/locales/ko.yml
@@ -1,7 +1,6 @@
 # Korean strings
 ko:
   default_mentionsl_info: 알림을 받을 기본 사용자를 나타내며, 쉼표로 구분 (e.g. @all, @here)
-  error_messenger_invalid_url: 유효한 URL이 아님
   label_messenger_contact_created: "%{project_url} - *%{user}*님이 연락처(%{url})를 만들었습니다."
   label_messenger_contact_updated: "%{project_url} - *%{user}*님이 연락처(%{url})를 수정했습니다."
   label_messenger_db_entry_created: "%{project_url} - *%{user}*님이 데이터베이스 항목(%{url})을 만들었습니다."