diff --git a/lib/faraday/request/retry.rb b/lib/faraday/request/retry.rb
index 5324f6e71..9640df693 100644
--- a/lib/faraday/request/retry.rb
+++ b/lib/faraday/request/retry.rb
@@ -1,3 +1,5 @@
+require 'date'
+
 module Faraday
   # Catches exceptions and retries each request a limited number of times.
   #