The patched test is a recursion function. We have lower stack size, so we hit SystemStackError sooner than on other platforms. #361 test_insns.rb:389:in `block in <top (required)>': # recursive once def once n return %r/#{ if n == 0 true else once(n-1) # here end }/ox end x = once(128); x = once(7); x = once(16); x =~ "true" && $~ #=> "" (expected "true") once Stderr output is not empty bootstraptest.tmp.rb:3:in `once': stack level too deep (SystemStackError) from bootstraptest.tmp.rb:7:in `block in once' from bootstraptest.tmp.rb:3:in `once' from bootstraptest.tmp.rb:7:in `block in once' from bootstraptest.tmp.rb:3:in `once' from bootstraptest.tmp.rb:7:in `block in once' from bootstraptest.tmp.rb:3:in `once' from bootstraptest.tmp.rb:7:in `block in once' from bootstraptest.tmp.rb:3:in `once' ... 125 levels... from bootstraptest.tmp.rb:3:in `once' from bootstraptest.tmp.rb:7:in `block in once' from bootstraptest.tmp.rb:3:in `once' from bootstraptest.tmp.rb:11:in `<main>' Test_insns.rb FAIL 1/187 FAIL 1/1197 tests failed Make: *** [uncommon.mk:666: yes-btest-ruby] Error 1 --- a/bootstraptest/test_insns.rb +++ b/bootstraptest/test_insns.rb @@ -248,7 +248,7 @@ end }/ox end - x = once(128); x = once(7); x = once(16); + x = once(32); x = once(7); x = once(16); x =~ "true" && $~ }, [ 'once', <<~'},', ], # {