diff --git a/bootstraptest/test_knownbug.rb b/bootstraptest/test_knownbug.rb
index 0fc902b552..43257dad81 100644
--- a/bootstraptest/test_knownbug.rb
+++ b/bootstraptest/test_knownbug.rb
@@ -40,3 +40,6 @@ assert_equal 'ok', %q{
   vs1 == vs2 ? :ok : :ng
 }, '[ruby-dev:32329]'
 
+assert_equal '..f00000000', %q{
+  sprintf("%x", -2**32)
+}, '[ruby-dev:32351]'