diff --git a/actionpack/test/abstract_unit.rb b/actionpack/test/abstract_unit.rb
index 7bcaf0a5eb3b2984d740377742daaef2df9b335f..660cabc554d568c2d87e95d0ab046a7bf23e90af 100644
--- a/actionpack/test/abstract_unit.rb
+++ b/actionpack/test/abstract_unit.rb
@@ -1,5 +1,11 @@
 require File.expand_path('../../../load_paths', __FILE__)
 
+lib = File.expand_path("#{File.dirname(__FILE__)}/../lib")
+$:.unshift(lib) unless $:.include?('lib') || $:.include?(lib)
+
+activemodel_path = File.expand_path('../../../activemodel/lib', __FILE__)
+$:.unshift(activemodel_path) if File.directory?(activemodel_path) && !$:.include?(activemodel_path)
+
 $:.unshift(File.dirname(__FILE__) + '/lib')
 $:.unshift(File.dirname(__FILE__) + '/fixtures/helpers')
 $:.unshift(File.dirname(__FILE__) + '/fixtures/alternate_helpers')