diff --git a/bootstraptest/test_knownbug.rb b/bootstraptest/test_knownbug.rb
index 9949ac5f29..2c60ac4d91 100644
--- a/bootstraptest/test_knownbug.rb
+++ b/bootstraptest/test_knownbug.rb
@@ -56,3 +56,6 @@ assert_normal_exit %q{
 assert_normal_exit %q{
   Encoding.compatible?("",0)
 }
+assert_normal_exit %q{
+  "".center(1, "\x80".force_encoding("utf-8"))
+}, '[ruby-dev:33807]'