diff --git a/actionpack/test/template/text_helper_test.rb b/actionpack/test/template/text_helper_test.rb
index 9962b7af3f..8b6c107a21 100644
--- a/actionpack/test/template/text_helper_test.rb
+++ b/actionpack/test/template/text_helper_test.rb
@@ -1,3 +1,4 @@
+# encoding: us-ascii
 require 'abstract_unit'
 require 'testing_sandbox'
 begin