I tried to compile a module generated with h2xs from Perl 5.8.1 under Perl 5.6.1 built using ithreads. It gets plenty of compilation errors because the arguments don't match: bool Perl_grok_numeric_radix(pTHX_ const char **sp, const char *send); Cheers, -Jan Index: ext/Devel/PPPort/PPPort.pm --- ext/Devel/PPPort/PPPort.pm.~1~ Wed Oct 8 20:30:43 2003 +++ ext/Devel/PPPort/PPPort.pm Wed Oct 8 20:30:43 2003 @@ -877,7 +877,7 @@ #endif #ifndef grok_numeric_radix -# define GROK_NUMERIC_RADIX(sp, send) grok_numeric_radix(sp, send) +# define GROK_NUMERIC_RADIX(sp, send) grok_numeric_radix(aTHX_ sp, send) #define grok_numeric_radix Perl_grok_numeric_radix End of Patch.Thread Next