diff --git a/activemodel/lib/active_model/mass_assignment_security.rb b/activemodel/lib/active_model/mass_assignment_security.rb
index c97420bc0339e6bbb34be0beeeec4bbf21126412..a7b4706906fcc6d353f0ce4d93e928426f3a9918 100644
--- a/activemodel/lib/active_model/mass_assignment_security.rb
+++ b/activemodel/lib/active_model/mass_assignment_security.rb
@@ -1,4 +1,5 @@
-require 'active_support/core_ext/class/attribute.rb'
+require 'active_support/core_ext/class/attribute'
+require 'active_support/core_ext/string/inflections'
 require 'active_model/mass_assignment_security/permission_set'
 require 'active_model/mass_assignment_security/sanitizer'