diff --git a/lib/shoulda/matchers/active_model/validate_inclusion_of_matcher.rb b/lib/shoulda/matchers/active_model/validate_inclusion_of_matcher.rb
index 2b6d94acc..84f329535 100644
--- a/lib/shoulda/matchers/active_model/validate_inclusion_of_matcher.rb
+++ b/lib/shoulda/matchers/active_model/validate_inclusion_of_matcher.rb
@@ -1,4 +1,5 @@
 require 'bigdecimal'
+require 'date'
 
 module Shoulda
   module Matchers