I'm trying to build numpy 1.2.1 as a module for a third-party python interpreter (custom-built, py2.4 linux x86_64) so that I can make calls to numpy from within it. Let's call this one interpreter A. The thing is, the system-wide python interpreter (also py2.4, let's call it B) from the vendor is built with --enable-unicode=ucs4, while the custom one is with UCS2. Needless to say, when I try to build a module with B, I get an error when I try to import numpy in A -- it complains about undefined symbol _PyUnicodeUCS4_IsWhiteSpace. I've searched around and apparently there's no way around this but to compile a custom Python interpreter -- which I did (let's call it interpreter C), properly specifying the unicode string length (verifiable through sys.maxunicode). I managed to build numpy with C as well, surprisingly enough, but still the problem persists when I try to import it in interpreter C. Previously, when I built numpy using B, there were no problems when importing it in B, but A would complain. Perhaps there's an option when building numpy to specify the length of Unicode strings to be used, as when configuring Python builds? Or am I doing something else wrong? A few notes: Upgrading to newer versions of python and/or numpy is not an option - interpreter A will stay on this version of the grammar for the foreseeable future. Also, it is not possible to start the interpreter A in standalone mode to build numpy with it, as it needs some other libraries preloaded I know that this whole thing is a mess, but I'd appreciate any help I can get to make this work. If you need more information, please let me know, I'd be happy to oblige. Thanks to everybody for their time in advance.