Missing symbol upon loading module

I have a PHP extension written in C++ which I use for parsing and building WbXml documents. I have tested building and using it on a 32 bit x86 system running the following: PHP 4.3.10 GCC 3.3.5 Gentoo Linux 2.6.10-r4 Everything works fine on this configuration. I do however need the extension to run on a x86 64 bits machine using the following configuration: PHP 4.4.0 GCC 3.2.3 RedHat Enterprise Linux 3 2.4.21-15 Everything compiles fine, no errors. When PHP tries to load the module however, I get the following error: PHP Warning: Unknown(): Unable to load dynamic library '/usr/local/php4/extensions/php_wbxml.so' - /usr/local/php4/extensions/php_wbxml.so: undefined symbol: __gxx_personality_v0 in Unknown on line 0 The name of the module is, obviously, php_wbxml.so. What does this error mean? I have tried to explicitly link against libsupc++ (which, from what I can gather, should include the __gxx_personality_v0 symbol) but the same error remains. I have moved other modules without problems between the two systems but this one doesn't seem to work. Here's the config.m4 I am using: PHP_ARG_ENABLE(php_wbxml, whether to enable WbXml support, [--enable-php_wbxml Enable WbXml support]) if test "$PHP_PHP_WBXML" = "yes"; then PHP_REQUIRE_CXX() PHP_ADD_LIBRARY(stdc++, 1, PHP_WBXML_SHARED_LIBADD) AC_DEFINE(HAVE_PHP_WBXML, 1, [whether you have WbXml]) PHP_NEW_EXTENSION(php_wbxml, php_wbxml.cpp TextXmlDocument.cpp tinystr.cpp tinyxml.cpp tinyxmlerror.cpp tinyxmlparser.cpp WbXmlDocument.cpp XmlAttribute.cpp XmlDocument.cpp XmlElement.cpp XmlHandle.cpp XmlNode.cpp XmlText.cpp, $ext_shared) fi VERY grateful for any tips on how to proceed. Best regards David Olsson