diff --git a/cpi_feed.rb b/cpi_feed.rb
index 6040501..3689ca7 100644
--- a/cpi_feed.rb
+++ b/cpi_feed.rb
@@ -8,6 +8,7 @@ class CPIFeed < Sinatra::Base
   get '/' do
     resp = JSON.parse(Faraday.get(cpi_series_url).body)
 
+    expires 300, :public, :must_revalidate
     content_type :csv
     "cpi\n#{resp['Results']['series'].first['data'].first['value']}\n"
   end