diff --git a/app/registries/foreman/settings/general.rb b/app/registries/foreman/settings/general.rb
index 96b41976375e..e4f6ec66474e 100644
--- a/app/registries/foreman/settings/general.rb
+++ b/app/registries/foreman/settings/general.rb
@@ -1,5 +1,5 @@
 Foreman::SettingManager.define(:foreman) do
-  locales = -> { Hash['' => _("Browser locale")].merge(Hash[FastGettext.human_available_locales.map { |lang| [lang[1], lang[0]] }]) }
+  locales = -> { Hash['' => _("Browser locale")].merge(Hash[Foreman::Gettext::Support.human_available_locales.map { |lang| [lang[1], lang[0]] }]) }
   timezones = -> { Hash['' => _("Browser timezone")].merge(Hash[ActiveSupport::TimeZone.all.map { |tz| [tz.name, "(GMT #{tz.formatted_offset}) #{tz.name}"] }]) }
 
   category(:general, N_('General')) do
diff --git a/app/views/users/_form.html.erb b/app/views/users/_form.html.erb
index 16a6895c9f35..07873b5e6291 100644
--- a/app/views/users/_form.html.erb
+++ b/app/views/users/_form.html.erb
@@ -34,7 +34,7 @@
       <% end %>
       <%= textarea_f f, :description, :rows=> 5, :size => "col-md-4" %>
 
-      <%= selectable_f(f, :locale, FastGettext.human_available_locales,
+      <%= selectable_f(f, :locale, Foreman::Gettext::Support.human_available_locales,
                         { :include_blank => _('Browser locale') } , { :label => _('Language') } ) %>
 
       <%= time_zone_select_f(f, :timezone, Time.find_zone(@user.timezone) || Time.find_zone!('UTC'), { :include_blank => _('Browser timezone') }) %>
diff --git a/config/puma/production.rb b/config/puma/production.rb
index 28fb8eb482ae..85cb03a67545 100644
--- a/config/puma/production.rb
+++ b/config/puma/production.rb
@@ -65,5 +65,5 @@
 # in development environment and little less on production. Let's eager load languages
 # for production before forking to save memory on CoW operating systems.
 before_fork do
-  FastGettext.human_available_locales
+  Foreman::Gettext::Support.human_available_locales
 end
diff --git a/extras/dynflow-sidekiq.rb b/extras/dynflow-sidekiq.rb
index 892e01c7cf43..cae01e76a9a7 100644
--- a/extras/dynflow-sidekiq.rb
+++ b/extras/dynflow-sidekiq.rb
@@ -10,7 +10,7 @@
   # Loading and initializing of all gettext languages takes about 100ms per language
   # in development environment and little less on production. Let's eager load languages
   # but only for production.
-  FastGettext.human_available_locales
+  Foreman::Gettext::Support.human_available_locales
 end
 
 rails_env_file = File.expand_path('./config/environment.rb', rails_root)
diff --git a/lib/foreman/gettext/support.rb b/lib/foreman/gettext/support.rb
index 3057c3c9cfc4..814b6ecf9b57 100644
--- a/lib/foreman/gettext/support.rb
+++ b/lib/foreman/gettext/support.rb
@@ -3,6 +3,8 @@
 module Foreman
   module Gettext
     module Support
+      @@mutex = Mutex.new
+
       def self.detect_locale_type
         if Rails.env.development?
           :po
@@ -44,29 +46,21 @@ def self.add_text_domain(locale_domain, locale_dir)
 
       # Loading all available locales to get the language translation is slow
       # (2 seconds for 20 languages), so let's lazy load that.
-      FastGettext.class_eval do
-        attr_accessor :mutex, :locales
-
-        self.mutex = Mutex.new
-
-        def human_available_locales
-          original_locale = FastGettext.locale
-          mutex.synchronize do
-            return locales if locales
-            Rails.logger.debug "Loading and caching all available locales"
-            locales = []
-            FastGettext.default_available_locales.sort.each do |locale|
-              FastGettext.locale = locale
-              # TRANSLATORS: Provide locale name in native language (e.g. Deutsch instead of German)
-              human_locale = _("locale_name")
-              human_locale = locale if human_locale == "locale_name"
-              locales << [human_locale, locale]
-            end
-            locales
+      def self.human_available_locales
+        original_locale = FastGettext.locale
+        @@mutex.synchronize do
+          return @@locales if @@locales
+          Rails.logger.debug "Loading and caching all available locales"
+          @@locales = FastGettext.default_available_locales.sort.map do |locale|
+            FastGettext.locale = locale
+            # TRANSLATORS: Provide locale name in native language (e.g. Deutsch instead of German)
+            human_locale = _("locale_name")
+            human_locale = locale if human_locale == "locale_name"
+            [human_locale, locale]
           end
-        ensure
-          FastGettext.locale = original_locale
         end
+      ensure
+        FastGettext.locale = original_locale
       end
     end
   end