diff --git a/activemodel/test/cases/helper.rb b/activemodel/test/cases/helper.rb
index 8bcbe54651..8578ab7dbd 100644
--- a/activemodel/test/cases/helper.rb
+++ b/activemodel/test/cases/helper.rb
@@ -1,5 +1,8 @@
 require File.expand_path('../../../../load_paths', __FILE__)
 
+lib = File.expand_path("#{File.dirname(__FILE__)}/../../lib")
+$:.unshift(lib) unless $:.include?('lib') || $:.include?(lib)
+
 require 'config'
 require 'active_model'