mysql2 install fail

bash-3.2$ sudo gem install mysql2
Building native extensions.  This could take a while...
ERROR:  Error installing mysql2:
        ERROR: Failed to build gem native extension.

        /Users/slim/.rvm/rubies/ruby-1.9.3-head/bin/ruby extconf.rb
checking for rb_thread_blocking_region()... yes
checking for rb_wait_for_single_fd()... yes
checking for mysql.h... yes
checking for errmsg.h... yes
checking for mysqld_error.h... yes
creating Makefile

make
compiling client.c
In file included from /Users/slim/.rvm/rubies/ruby-1.9.3-head/include/ruby-1.9.1/ruby.h:32,
                 from ./mysql2_ext.h:8,
                 from client.c:1:
/Users/slim/.rvm/rubies/ruby-1.9.3-head/include/ruby-1.9.1/ruby/ruby.h:105: error: size of array ‘ruby_check_sizeof_long’ is negative
/Users/slim/.rvm/rubies/ruby-1.9.3-head/include/ruby-1.9.1/ruby/ruby.h:109: error: size of array ‘ruby_check_sizeof_voidp’ is negative
In file included from /Users/slim/.rvm/rubies/ruby-1.9.3-head/include/ruby-1.9.1/ruby/intern.h:34,
                 from /Users/slim/.rvm/rubies/ruby-1.9.3-head/include/ruby-1.9.1/ruby/ruby.h:1361,
                 from /Users/slim/.rvm/rubies/ruby-1.9.3-head/include/ruby-1.9.1/ruby.h:32,
                 from ./mysql2_ext.h:8,
                 from client.c:1:
/Users/slim/.rvm/rubies/ruby-1.9.3-head/include/ruby-1.9.1/ruby/st.h:67: error: size of array ‘st_check_for_sizeof_st_index_t’ is negative
client.c: In function ‘rb_raise_mysql2_error’:
client.c:96: warning: ISO C90 forbids mixed declarations and code
client.c: In function ‘rb_mysql_client_socket’:
client.c:582: warning: ISO C90 forbids mixed declarations and code
make: *** [client.o] Error 1


Gem files will remain installed in /Users/slim/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/mysql2-0.3.10 for inspection.
Results logged to /Users/slim/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/mysql2-0.3.10/ext/mysql2/gem_make.out
bash-3.2$