# \[solved\] CAPTCHA gem: undefined method \`stringFT'

**URL:** <https://www.ruby-forum.com/t/solved-captcha-gem-undefined-method-stringft/170947>\
**Category:** Rails\
**Created:** [June 24, 2009, 11:15am UTC](https://www.ruby-forum.com/t/solved-captcha-gem-undefined-method-stringft/170947 "2009-06-24T11:15:52Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![gigi33](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/d78d45/32.png) [@gigi33](https://www.ruby-forum.com/u/gigi33)\
**Post date:** [June 24, 2009, 11:15am UTC](https://www.ruby-forum.com/t/solved-captcha-gem-undefined-method-stringft/170947/1 "2009-06-24T11:15:52Z")

</div>

Since it took me quite some time to resolve this problem, I hope this  
post will be useful for someone else.

I am using the CAPTCHA gem in my application and always got the  
following error:

undefined method `stringFT’ for GD::Image:Class

It turns out that I was missing the GD libs for ruby. I’m on ubuntu, so  
a quick  
sudo install libgd-ruby  
solved the problem for me.

I also found resources for OS X and Red Hat Enterprise Linux 4:

OS X: [404-返回首页](http://lukewarmtapioca.com/2007/02/06/gd-on-osx-and-ruby-stringft/)  
Red Hat:  
[http://involution.com/2007/06/11/problems-with-rubys-captcha-gem/](http://involution.com/2007/06/11/problems-with-rubys-captcha-gem/)