diff --git a/config/routes.rb b/config/routes.rb
index 9d5c974a..3dfc4c85 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,5 +1,10 @@
 # frozen_string_literal: true
 
+# Como el sitio puede contener puntos, no queremos confundirlos con
+# tipos de contenido, por ejemplo que /sites/site.org no intente service
+# text/org.
+SITE_ID_RE = %r{[^/]+}.freeze
+
 Rails.application.routes.draw do
   devise_for :usuaries
   get '/.well-known/change-password', to: redirect('/usuaries/edit')
@@ -18,7 +23,7 @@ Rails.application.routes.draw do
           resources :remote_flags, only: %i[show]
         end
 
-        resources :sites, only: %i[index], constraints: { site_id: /[a-z0-9\-.]+/, id: /[a-z0-9\-.]+/ } do
+        resources :sites, only: %i[index], constraints: { site_id: SITE_ID_RE, id: SITE_ID_RE } do
           get  :'invitades/cookie', to: 'invitades#cookie'
           post :'posts/:layout', to: 'posts#create', as: :posts
 
@@ -42,12 +47,12 @@ Rails.application.routes.draw do
   # Las rutas privadas empiezan con una ruta única para poder hacer un
   # alias en nginx sin tener que usar expresiones regulares para
   # detectar el nombre del sitio.
-  get '/sites/private/:site_id(*file)', to: 'private#show', constraints: { site_id: %r{[^/]+} }
+  get '/sites/private/:site_id(*file)', to: 'private#show', constraints: { site_id: SITE_ID_RE }
   get '/env.js', to: 'env#index'
 
   match '/api/v3/projects/:site_id/notices' => 'api/v1/notices#create', via: %i[post]
 
-  resources :sites, constraints: { site_id: %r{[^/]+}, id: %r{[^/]+} } do
+  resources :sites, constraints: { site_id: SITE_ID_RE, id: SITE_ID_RE } do
     # Gestionar actualizaciones del sitio
     get 'pull', to: 'sites#fetch'
     post 'pull', to: 'sites#merge'