Specific gem situation

I’m missing something (wouldn’t be the first time).

Xubuntu, fresh build and install of Ruby 1.8.7 (no apt-get install
here), but continually get zlib errors when trying to build rubygems.

Now, I know this isn’t a Ruby issue, so my apologies, but if anyone
has run into this before, I’d appreciate a point in the right
direction. Can’t find it, but I’m assuming there’s a
configure/makefile option to point to the correct zlib (the library is
installed, as are the development files). Also, the solutions I’ve
googled seem long-winded and overkill.

Thanks if you know something that pertains,