diff --git a/Gemfile b/Gemfile
index 8627c685..7933f0d2 100644
--- a/Gemfile
+++ b/Gemfile
@@ -234,8 +234,7 @@ group :development do
   gem 'spring-commands-rspec'
   # to open mails
   gem 'letter_opener'
-  # view mail at /letter_opener/
-  gem 'letter_opener_web', '~> 1.0'
+  gem 'letter_opener_web'
   # as deployment system
   gem 'mina'
   # as debugger on error pages
diff --git a/Gemfile.lock b/Gemfile.lock
index 52965d29..110b19bd 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -718,8 +718,7 @@ DEPENDENCIES
   json-schema
   leaflet-rails
   letter_opener
-  letter_opener_web (~> 1.0)
-  mimemagic (~> 0.3.6)
+  letter_opener_web
   mina
   mini_magick
   money-rails
diff --git a/config/routes.rb b/config/routes.rb
index e2332ce2..a76268c5 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,4 +1,5 @@
 Osem::Application.routes.draw do
+  mount LetterOpenerWeb::Engine, at: '/letter_opener' if Rails.env.development?
 
   mount LetterOpenerWeb::Engine, at: '/letter_opener' if Rails.env.development?