root@sergio-laptop:/home/srps# gem i date-performance
Building native extensions.  This could take a while...
ERROR:  Error installing date-performance:
  ERROR: Failed to build gem native extension.

/usr/bin/ruby1.9.1 extconf.rb
creating Makefile

make
Makefile:143: *** target pattern contains no `%'.  Stop.


Gem files will remain installed in /var/lib/gems/1.9.1:/home/srps/.gem/ruby/1.9.1/gems/date-performance-0.4.8 for inspection.
Results logged to /var/lib/gems/1.9.1:/home/srps/.gem/ruby/1.9.1/gems/date-performance-0.4.8/ext/gem_make.out