diff --git a/activemodel/lib/active_model/validations/validates.rb b/activemodel/lib/active_model/validations/validates.rb
index 4c82a993ae199d25adb98ffb4745d48823bf9f16..90b244228a112075e3edc852fba5f3e0496471b9 100644
--- a/activemodel/lib/active_model/validations/validates.rb
+++ b/activemodel/lib/active_model/validations/validates.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/hash/slice'
+
 module ActiveModel
   module Validations
     module ClassMethods