diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11da68a94..a65de6096 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 - Improved contextual help with a modal dialog
 - Updated translations
 - Refactored translations to help merging Crowdin PR
+- Fix a bug: unable to create new availabilities if SLOT_DURATION is not defined
 
 ## v4.3.1 2020 March 04
 
diff --git a/app/assets/javascripts/controllers/home.js b/app/assets/javascripts/controllers/home.js
index 7bbfecab7..1d961ae00 100644
--- a/app/assets/javascripts/controllers/home.js
+++ b/app/assets/javascripts/controllers/home.js
@@ -41,7 +41,6 @@ Application.Controllers.controller('HomeController', ['$scope', '$stateParams',
       // We set the home page content, with the directives replacing the placeholders
       $scope.homeContent = insertDirectives(settingsPromise.home_content);
 
-
       // for admins, setup the tour on login
       $scope.$watch('currentUser', function (newValue, oldValue) {
         if (!oldValue && newValue && newValue.role === 'admin') {
diff --git a/app/models/availability.rb b/app/models/availability.rb
index 0a01d0da7..eefba45c2 100644
--- a/app/models/availability.rb
+++ b/app/models/availability.rb
@@ -159,9 +159,9 @@ class Availability < ActiveRecord::Base
   private
 
   def length_must_be_slot_multiple
-    if end_at < (start_at + Rails.application.secrets.slot_duration.minutes)
-      errors.add(:end_at, I18n.t('availabilities.length_must_be_slot_multiple', MIN: Rails.application.secrets.slot_duration))
-    end
+    return unless end_at < (start_at + ApplicationHelper::SLOT_DURATION.minutes)
+
+    errors.add(:end_at, I18n.t('availabilities.length_must_be_slot_multiple', MIN: ApplicationHelper::SLOT_DURATION))
   end
 
   def should_be_associated