diff --git a/activesupport/lib/active_support/core_ext/exception.rb b/activesupport/lib/active_support/core_ext/exception.rb
index c22013beef..9564591e36 100644
--- a/activesupport/lib/active_support/core_ext/exception.rb
+++ b/activesupport/lib/active_support/core_ext/exception.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/pathname'
+
 module ActiveSupport
   FrozenObjectError = RUBY_VERSION < '1.9' ? TypeError : RuntimeError
 end