Support ticket #1951: couldn't find ruby.h

Hi,

I'm somehow having trouble compiling the C extension from the installation instructions. I am getting this error:

checking for ruby.h... no
couldn't find ruby.h (required)
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

mkmf.log shows:

have_header: checking for ruby.h... -------------------- no

"gcc -E -I. -I/usr/lib/ruby/1.8/x86_64-linux -I.    -fno-strict-aliasing -g -g -O2  -fPIC    conftest.c -o conftest.i"
In file included from /usr/lib/ruby/1.8/x86_64-linux/ruby.h:40,
                 from conftest.c:1:
/usr/include/stdlib.h:33:20: error: stddef.h: No such file or directory
In file included from /usr/include/stdio.h:75,
                 from /usr/lib/ruby/1.8/x86_64-linux/ruby.h:58,
                 from conftest.c:1:
/usr/include/libio.h:53:21: error: stdarg.h: No such file or directory
In file included from /usr/lib/ruby/1.8/x86_64-linux/ruby.h:95,
                 from conftest.c:1:
/usr/include/limits.h:125:26: error: no include path in which to search for limits.h
checked program was:
/* begin */
1: [/tags/include #include] <ruby.h>
/* end */

--------------------

Here are a few details of my installed packages:

Ruby: ruby 1.8.7 (2010-08-16 patchlevel 302) [x86_64-linux]

Distro: Debian Squeeze

Vim is Vim 7.2

I have ruby-dev installed too which I think is required for this (got from googling). I also have libruby1.8 and ruby1.8-dev.

Thanks for support!