diff --git a/config/routes/api.rb b/config/routes/api.rb
index 08e67ab87b..4ce4751c4d 100644
--- a/config/routes/api.rb
+++ b/config/routes/api.rb
@@ -18,8 +18,8 @@ namespace :api, format: false do
 
         # foreign custom emojis are encoded as shortcode@domain.tld
         # the constraint prevents rails from interpreting the ".tld" as a filename extension
-        post '/react/:id', to: 'reactions#create', constraints: { id: /[^\/]+/ }
-        post '/unreact/:id', to: 'reactions#destroy', constraints: { id: /[^\/]+/ }
+        post '/react/:id', to: 'reactions#create', constraints: { id: %r{[^/]+} }
+        post '/unreact/:id', to: 'reactions#destroy', constraints: { id: %r{[^/]+} }
 
         resource :bookmark, only: :create
         post :unbookmark, to: 'bookmarks#destroy'