Finally, I was able to narrow it down to a bug in macruby. I had to edit rbconfig.rb to remove "-arch i386" from ARCH_FLAG, leaving it with just "-arch x86_64" which works for me. Then I had to remove the compiled rbconfig.rbo. All of the above leaves me with the bus error below. How do I debug it? Thanks, Joel --- biggie:mysql-gem joelr$ macrake (in /Users/joelr/work/ruby/mysql-gem) rake-compiler must be configured first to enable cross-compilation mkdir -p tmp/universal-darwin10.0/mysql_api/1.9.0 cd tmp/universal-darwin10.0/mysql_api/1.9.0 /Library/Frameworks/MacRuby.framework/Versions/0.6/usr/bin/macruby -I. ../../../../ext/mysql_api/extconf.rb checking for mysql_ssl_set()... yes checking for rb_str_set_len()... yes checking for rb_thread_start_timer()... no checking for mysql.h... yes creating Makefile cd - cd tmp/universal-darwin10.0/mysql_api/1.9.0 GNU Make 3.81 Copyright (C) 2006 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. This program built for i386-apple-darwin10.0.0 gmake /usr/bin/gcc -I. -I/Library/Frameworks/MacRuby.framework/Versions/0.6/usr/include/ruby-1.9.0/universal-darwin10.0 -I/Library/Frameworks/MacRuby.framework/Versions/0.6/usr/include/ruby-1.9.0/ruby/backward -I/Library/Frameworks/MacRuby.framework/Versions/0.6/usr/include/ruby-1.9.0 -I../../../../ext/mysql_api -DHAVE_MYSQL_SSL_SET -DHAVE_RB_STR_SET_LEN -DHAVE_MYSQL_H -I/usr/local/mysql/include -g -Os -arch x86_64 -fno-common -D_P1003_1B_VISIBLE -DSIGNAL_WITH_VIO_CLOSE -DSIGNALS_DONT_BREAK_READ -DIGNORE_SIGHUP_SIGQUIT -DDONT_DECLARE_CXA_PURE_VIRTUAL -fno-common -fexceptions -fno-common -pipe -O3 -g -Wall -Wno-parentheses -arch x86_64 -o mysql.o -c /usr/bin/gcc -dynamic -bundle -undefined suppress -flat_namespace -arch x86_64 -o mysql_api.bundle mysql.o -L. -L/Library/Frameworks/MacRuby.framework/Versions/0.6/usr/lib -arch x86_64 -lmacruby -L/usr/local/mysql/lib -lmysqlclient -lz -lm -lmygcc cd - cp tmp/universal-darwin10.0/mysql_api/1.9.0/mysql_api.bundle lib/mysql_api.bundle /Library/Frameworks/MacRuby.framework/Versions/0.6/usr/bin/macruby -w -Ilib:bin:test:. -e 'require "rubygems"; require "test/unit"; require "test/test_mysql.rb"' -- unknown: warning: instance variable @post_install_hooks not initialized unknown: warning: instance variable @post_uninstall_hooks not initialized unknown: warning: instance variable @pre_uninstall_hooks not initialized unknown: warning: instance variable @pre_install_hooks not initialized unknown: warning: instance variable @suffix_pattern not initialized unknown: warning: instance variable @path not initialized unknown: warning: instance variable @home not initialized /Library/Frameworks/MacRuby.framework/Versions/0.6/usr/lib/ruby/1.9.0/test/unit/assertions.rb:31: warning: shadowing outer local variable - line Loaded suite -e Started .EEunknown: [BUG] Bus Error MacRuby version 0.6 (ruby 1.9.0) [universal-darwin10.0, x86_64] rake aborted! Command failed with status (): [/Library/Frameworks/MacRuby.framework/Vers...] (See full trace by running task with --trace) --- http://twitter.com/wagerlabs